Fix inner callback decorators with partials

[bdraco]

Proposed change

The partials were wrapped with @callback, but the inner function needed to be wrapped with @callback instead. The check in async_listen was wrong and did not match the check in HassJob. Everything worked ok because the incorrectly decorated function were all run_immediately which always ran them as callbacks anyways.

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (websocket_api) you are listed as a code owner for? Thanks!

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[bdraco]

Still something wrong here.. will have to look later though as out of time right now

[bdraco]

I think this was actually working as expected because the check was wrong in both places so while it reported it would be run in the executor in in the repr it wouldn't actually be

Ie problem is mostly cosmetic but it does result in an extra asyncio.iscoroutine call every time a websocket subscription is made.

[bdraco]

Going to spend some more time digging at this to clean it up more.

[elupus]

Lgtm

[bdraco]

thanks