For luminous, the ceph_mgr service provide the
dashborad for ceph, and it need connect to cluster,
but now it failed to connect ceph cluster due to
ceph.client.admin.keyring missing, this ps to fix it.
Co-Authored-By: chenqiaomin <chen.qiaomin@99cloud.net>
Closes-Bug: #1768462
Change-Id: Idb24661bc5674780db390220ca02e22975490663