nova-cell: Stop printing ceph keys in output

Change-Id: Ib6719a033b37be3e248b682795b7243c60b22b84
(cherry picked from commit dbc6324)

Author: mnasiadka

ansible/roles/nova-cell/tasks/external_ceph.yml

@@ -136,6 +136,7 @@
       enabled: "{{ cinder_backend_ceph }}"
   notify:
     - Restart nova-libvirt container
+  no_log: True
 
 - name: Ensuring config directory has correct owner and permission
   become: true