enable ceph-mon.target service after monitor start
enable ceph-mon.target service after monitor start

ceph-create-keys unit file was removed here:

* https://github.com/ceph/ceph/commit/8bcb4646b6b9846bb965cdec3ca2a21eb3b26bab
* https://github.com/ceph/ceph/commit/dc5fe8d415858358bd0baf5d8dce0a753f5e0cea

As a consequence the systemctl preset command now fails to run since the
unit does not exist anymore. Due to the redirection in /dev/null we
don't know what's happening.

Ultimately the mon unit doesn't get enabled and the mon service won't
start after reboot.
Removing the old/non-existent unit makes the command succeed now.

ceph fix: https://github.com/ceph/ceph/pull/14226

Signed-off-by: WingkaiHo <9d492f01383aac44573478744b0f9d6a634aecff@163.com>
Co-Authored-By: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

travmi/ceph-ansible,jtaleric/ceph-ansible,albertomurillo/ceph-ansible,bengland2/ceph-ansible,bengland2/ceph-ansible,WingkaiHo/ceph-ansible,WingkaiHo/ceph-ansible,font/ceph-ansible,albertomurillo/ceph-ansible,albertomurillo/ceph-ansible,travmi/ceph-ansible,jtaleric/ceph-ansible,ceph/ceph-ansible,ceph/ceph-ansible,WingkaiHo/ceph-ansible,fgal/ceph-ansible,font/ceph-ansible,fgal/ceph-ansible