s3:dbwrap_watch: let dbwrap_watched_delete() call dbwrap_watched_record_storev(num_db...

s3:dbwrap_watch: let dbwrap_watched_delete() call dbwrap_watched_record_storev(num_dbufs=0)

dbwrap_watched_record_storev() will handle the high level storev and
delete, it will find out if we can remove the record as there's no value
and also no watchers to be stored.

This is no real change for now as dbwrap_watched_record_wakeup() will
always exits with wrec->watchers.count = 0, but that will change in the next
commits.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>