tests: Run samba_tool.gpo tests against backup testenvs

tests: Run samba_tool.gpo tests against backup testenvs

Run the GPO tests against the backup/restore testenvs.

Because the backup/restore preserves the NTACLs of the sysvol files,
running the GPO tests against the backup testenvs is a good sanity-
check. If fact it highlights that there is currently a problem with
restoring the GPO files - this shows up in 'samba-tool gpo aclcheck',
but we never noticed it until now.

NTACL backup works slightly different for offline backups, and rename
backups end up with more sysvol files, so run the tests against both
these envs.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13676

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>