[mqtt.homeassistant] Discovered things never get removed from the inbox

[ccutrer]

Expected Behavior

Have an MQTT discovered Home Assistant device. Then delete all of the discovery topics from MQTT. The Thing should disappear from the openHAB Inbox (at the least it should not come back after openHAB is restarted).

Current Behavior

Things stay in the inbox forever. You can manually delete them, and they won't come back. This is particularly painful in conjunction with #16600 - I have a copy of every Home Assistant device (hundreds!) in my Inbox with the old thing type ID, since I've gone back and forth several times on running that PR or the released version of the binding.

Possible Solution

At boot, remove all inbox items for Home Assistant; they'll come back shortly when the discovery messages come in.

Your Environment

• Version used: 4.3.0-SNAPSHOT
• Operating System and version (desktop or mobile, Windows 10, Raspbian Buster, ...): Ubuntu 22.04 jammy