Consider this:
1) n1 is the topology coordinator
2) n1 schedules and executes a tablet repair with session id s1 for a
tablet on n3 an n4.
3) n3 and n4 take and store the in _rs._repair_compaction_locks[s1]
4) n1 steps down before it executes
locator::tablet_transition_stage::end_repair
5) n2 becomes the new topology coordinator
6) n2 runs locator::tablet_transition_stage::repair again
7) n3 and n4 try to take the lock again and hangs since the lock is
already taken.
To avoid the deadlock, we can throw in step 7 so that n2 will
proceed to end_repair stage and release the lock. After that, the
scheduler could schedule the tablet repair request again.
Fixes#26346Closesscylladb/scylladb#27163
da5cc13e97