tests: Run backup tests against restoredc (SMBv1 disabled)

tests: Run backup tests against restoredc (SMBv1 disabled)

Running the backup tests against the restoredc highlights that the
backup online/rename commands don't work if SMBv1 is disabled. Note that
the offline commands still work because they don't rely on an SMB
connection to the server.

(Note that running the backup tests against the restoredc is probably a
good idea anyway, to prove that there's no limit to the number of times
you can restore a domain from backup, i.e. we support more than just a
one-off restore).

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

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>