The debug REST API is not serving recent states (less than 2 days old)
We've noticed that one of our DendrETH relay nodes failed to resync recently because it was not able to obtain a recent `BeaconState` from the `unstable.mainnet.beacon-api.nimbus.team` Beacon API server.

Here is a quick command that can be used to reproduce the issue:

```
for i in $(seq -f "%02g" 1 32); do; curl http://unstable.mainnet.beacon-api.nimbus.team/eth/v2/debug/beacon/states/90108$i | tee state-90108$i; done
```

Output:

```
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    117      0 --:--:-- --:--:-- --:--:--   117
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    124      0 --:--:-- --:--:-- --:--:--   124
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0     92      0 --:--:-- --:--:-- --:--:--    92
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    105      0 --:--:-- --:--:-- --:--:--   105
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    112      0 --:--:-- --:--:-- --:--:--   112
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    123      0 --:--:-- --:--:-- --:--:--   123
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    112      0 --:--:-- --:--:-- --:--:--   112
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    116      0 --:--:-- --:--:-- --:--:--   116
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0     68      0 --:--:-- --:--:-- --:--:--    68
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    106      0 --:--:-- --:--:-- --:--:--   106
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    122      0 --:--:-- --:--:-- --:--:--   122
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    106      0 --:--:-- --:--:-- --:--:--   106
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    120      0 --:--:-- --:--:-- --:--:--   120
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    116      0 --:--:-- --:--:-- --:--:--   117
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    115      0 --:--:-- --:--:-- --:--:--   115
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    120      0 --:--:-- --:--:-- --:--:--   121
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0     73      0 --:--:-- --:--:-- --:--:--    73
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    124      0 --:--:-- --:--:-- --:--:--   125
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    111      0 --:--:-- --:--:-- --:--:--   111
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    115      0 --:--:-- --:--:-- --:--:--   115
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    116      0 --:--:-- --:--:-- --:--:--   116
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0     58      0 --:--:-- --:--:-- --:--:--    58
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    110      0 --:--:-- --:--:-- --:--:--   110
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    105      0 --:--:-- --:--:-- --:--:--   105
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    106      0 --:--:-- --:--:-- --:--:--   106
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    114      0 --:--:-- --:--:-- --:--:--   114
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    110      0 --:--:-- --:--:-- --:--:--   110
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    104      0 --:--:-- --:--:-- --:--:--   104
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    114      0 --:--:-- --:--:-- --:--:--   114
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    116      0 --:--:-- --:--:-- --:--:--   116
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0     63      0 --:--:-- --:--:-- --:--:--    63
{"code":404,"message":"Could not get requested state"}  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    54  100    54    0     0    103      0 --:--:-- --:--:-- --:--:--   103
{"code":404,"message":"Could not get requested state"}%
➜  ~
```