qa: workunits/mon/rbd_snaps_ops.sh: ENOTSUP on snap rm from copied pool

'rados cppool' copies the contents but that doesn't make the destination
pool an unmanaged snaps pool.  Therefore, we must get an ENOTSUP when
we try to remove an unmanaged snap from a not-unmanaged pool.


Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>