Update ceph-mon keyrings

Since the fetch script fetched _all_ keyrings from the ceph-mon
container, the ceph-mon container must contain all keyrings. This
setup works AIO but was broken on multinode because the ceph-mon
container did not have the radosgw keyring. This issue affects every
multinode install regardless of using the radosgw or not.

TrivialFix

Change-Id: Ie416de1a5275862da6d77ef0dd174e85e499fc0f