ctdb-daemon: Free up record data if a call request is deferred

ctdb-daemon: Free up record data if a call request is deferred

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13029

If a call request for a key (migration request) is in flight, then all
the subsequent call requests for the same key are deferred.  In that case,
the data corresponding to key read from the local tdb is useless and there
is no need to keep it around.  Once the deferred call is reprocessed,
the data corresponding to that key will be fetched again.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
(cherry picked from commit 77c17b03cfc4734142fd86ba3cdd9663e75f34e3)