Make job cleanup service not sleep if it's not running any more

[artem-shelkovnikov]

All other services do this.

Rationale: If the service is interrupted it should stop doing whatever it's doing and quit.

It can happen due to asynchronous nature that the service is stopped right before the await self._sleeps.sleep(self.idling) is called. What happens is:

1. self.running is set to false
2. self._sleeps.cancel is called

But CancellableSleeps class allows adding new sleeps after cancellation happens, so service is not running but it will still sleep one last time before exiting. For job cleanup service this sleep will be 5 minutes by default, thus graceful cancellation will just hang for 5 minutes cause of it.

This change is just to "make it work" - we need to think about making CancellableSleeps not accept any more sleeps if cancelled.

[github-actions[bot]]

💔 Failed to create backport PR(s)

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To backport manually run: backport --pr 2786 --autoMerge --autoMergeMethod squash