[Bug] Incorrect mapping for 'TRADFRI SHORTCUT Button'.
**Describe the bug**
The switch has a single 'button' on it but presents in homekit as having 3 buttons with 'single press' actions. 'button 1' is triggered by a single short press, button 3 is triggered by a long press, button 2 is triggered when the long press is released (I assume this is some interpretation of a dimmer switch?)

**Related devices**
TRADFRI SHORTCUT Button

**To Reproduce**
Standard install 

**Expected behavior**
A single button presented to homekit with 'short press' and 'long press' actions attached. 

**MQTT messages**
Short press, long press, then release long press. 
```
[32mZigbee2MQTT:info [39m 2021-04-10 06:32:54: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"battery":60,"linkquality":86,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 07:28:59: MQTT publish: topic 'zigbee2mqtt/Spare Socket', payload '{"linkquality":55,"power_on_behavior":"off","state":"OFF","update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:25:55: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"battery":34,"linkquality":65,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:25:55: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"battery":34,"linkquality":65,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:25:55: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"action":"on","battery":34,"linkquality":68,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:26:10: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"action":"brightness_move_up","action_rate":83,"battery":34,"linkquality":68,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:26:16: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"action":"brightness_stop","battery":34,"linkquality":68,"update":{"state":"idle"},"update_available":false}'
[32mZigbee2MQTT:info [39m 2021-04-10 08:26:16: MQTT publish: topic 'zigbee2mqtt/Night Button', payload '{"action":"brightness_stop","battery":34,"linkquality":68,"update":{"state":"idle"},"update_available":false}'
```

**Versions used**
Please provide the version of the following pieces of software:
 - This plugin: v1.1.3
 - Homebridge: v1.3.4
 - Zigbee2MQTT (can be found in MQTT topic `zigbee2mqtt/bridge/info`): v1.18.2