When a tablet transitions to a post-cleanup stage on the leaving replica
we deallocate its storage group. Before the storage can be deallocated
and destroyed, we must make sure it's cleaned up and stopped properly.
Normally this happens during the tablet cleanup stage, when
table::cleanup_table is called, so by the time we transition to the next
stage the storage group is already stopped.
However, it's possible that tablet cleanup did not run in some scenario:
1. The topology coordinator runs tablet cleanup on the leaving replica.
2. The leaving replica is restarted.
3. When the leaving replica starts, still in `cleanup` stage, it
allocates a storage group for the tablet.
4. The topology coordinator moves to the next stage.
5. The leaving replica deallocates the storage group, but it was not
stopped.
To address this scenario, we always stop the storage group when
deallocating it. Usually it will be already stopped and complete
immediately, and otherwise it will be stopped in the background.
Fixesscylladb/scylladb#24857Fixesscylladb/scylladb#24828Closesscylladb/scylladb#24896
(cherry picked from commit fa24fd7cc3)
Closesscylladb/scylladb#24906
a57c51b9d7