ctdb_mutex_ceph_rados_helper: fix deadlock via lock renewals

ctdb_mutex_ceph_rados_helper: fix deadlock via lock renewals

RADOS locks without expiry persist indefinitely. This results in CTDB
deadlock during failover if the recovery master dies unexpectedly, as
subsequently elected recovery master nodes can't obtain the recovery
lock.
Avoid deadlock by using a lock expiration time (10s by default), and
renewing it periodically.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13540

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Samuel Cabrero <scabrero@suse.de>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>