fix: availability checks not stopped on extension stop

[protyposis]

Clear the ping queue of the availability extension on stop, to prevent availability check (ping) cycles of unavailable devices continuing to run. This prevents the following issues:

• In case of a "soft" restart (e.g., via UI), the restart of the extension created additional availability check cycles, leading to every availability check executing twice (and thrice after the next restart, etc.).
• When a device is disabled, the UI asks for a restart. If that device is unavailable, and a check cycle therefore already running, the checks continue after the restart. To users, this looks like disabling of unavailable devices does not work.

Fixes #20021.

[protyposis]

I guess you won't like the test since it's written in a completely different style, but I don't understand the architecture of the existing tests.

[Koenkk]

Awesome, thanks for both reporting and fixing the issue! 😄

[dessfred]

Hi,

I have the same issue with the zigbee2mqtt add-on (version 1.36.1-1) for home assistant. How can I prevent ping of unavailable devices ? I don't find a file called 'availability.ts'.

Thank you.