s4-torture: add test for lease break after file unlink

s4-torture: add test for lease break after file unlink

When deleting a file, all leases granting handle caching lease to the
file should be recalled.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13458

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jun  1 02:57:46 CEST 2018 on sn-devel-144