rbd-mirror: remove callout when destroying pool replayer

rbd-mirror: remove callout when destroying pool replayer

If a pool replayer is removed in an error state (e.g. after failing to
connect to the remote cluster), its callout should be removed as well.
Otherwise, the error would persist causing "daemon health: ERROR"
status to be reported even after a new pool replayer is created and
started successfully.

Fixes: https://tracker.ceph.com/issues/65487
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
(cherry picked from commit b7e79642d53c1802ae1202c3f013677fcfd26b1b)