ctdb-recoverd: Process all the records for vacuum fetch in a loop

ctdb-recoverd: Process all the records for vacuum fetch in a loop

Processing one migration request at a time is very slow and processing
a batch of records can take longer than VacuumInterval.  This causes
subsequent vacuum fetch requests to be dropped.  The dropped records
can accumulate quickly and will cause the vacuum database traverse to
be quite expensive.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Fri Dec  5 17:06:58 CET 2014 on sn-devel-104