bg-mining-miner-target still can't get reached
I am trying to configure background mining but get strange results with various threads+target combinations.
My system a bit out of date: Windows 7 64 bit, Ryzen 7 5700x 8C/16T, I know that CPU is not officially supported but all other progs&games runs pretty fine.
Node is Monero 'Fluorine Fermi' (v0.18.2.2-release) pruned and fully synced.

So, with this params:

```
mining-threads=10
bg-mining-enable=1
bg-mining-ignore-battery=1
bg-mining-miner-target=100
# for fast bg-mining start
bg-mining-min-idle-interval=10
bg-mining-idle-threshold=10
```

I get only 5-6% CPU used by monerod and 95% overall idle.
If I set 32 threads (too much for 16T CPU) and target is still 100% I get 10-13% monerod usage.

