Fix restarting OSDs twice during a rolling update.

Fix restarting OSDs twice during a rolling update.

During a rolling update, OSDs are restarted twice currently. Once, by the
handler in roles/ceph-defaults/handlers/main.yml and a second time by tasks
in the rolling_update playbook. This change turns off restarts by the handler.
Further, the restart initiated by the rolling_update playbook is more
efficient as it restarts all the OSDs on a host as one operation and waits
for them to rejoin the cluster. The restart task in the handler restarts one
OSD at a time and waits for it to join the cluster.