Not completely sure this could actually have any ill effect, but if
`RemoveStatusService` fails to acquire a lock in an
`ActivityPub::ProcessingWorker` job processing a `Delete`, the status
is currently discarded and causes a job failure but the next time the
job is attempted, it will skip deleting the status due to it being
discarded.

This commit makes the behavior of `RemoveStatusService` a bit more consistent
in case of failure to acquire the lock.