Allow to distribute custom key with the role

Right now we have quite strong assumption that `nova_ceph_client` should be
present among clients to fetch. At the same time, in case the role is
included outside of the OSA context, ceph_client_filtered_clients might
not contain all users we expect to see.

With that we alter the logic to fetch nova key not only when role is launched
against compute host, but also when the client is present in the list.

Change-Id: I7810881a01b9d2f3d98a6c3ad590b9ea63358011

tasks/ceph_auth.yml

@@ -79,6 +79,7 @@
   command: virsh secret-get-value {{ nova_ceph_client_uuid }}
   when:
     - inventory_hostname in groups.nova_compute
+    - ceph_nova_secret is defined
   changed_when: false
   failed_when: false
   register: libvirt_nova_set

tasks/ceph_get_keyrings_from_files.yml

@@ -57,6 +57,7 @@
       stdout: "{{ (ceph_client_keys[nova_ceph_client] | regex_search('.*^\\s*key\\s*=\\s*(.*)$.*', '\\1', multiline=True))[0] }}"
   when:
     - inventory_hostname in groups.nova_compute
+    - nova_ceph_client in ceph_client_filtered_clients | map(attribute='name') | list
   delegate_to: localhost
   tags:
     - always

tasks/ceph_get_keyrings_from_mons.yml

@@ -61,6 +61,7 @@
   command: ceph auth get-key client.{{ nova_ceph_client }} --cluster {{ ceph_cluster_name }}
   when:
     - inventory_hostname in groups.nova_compute
+    - nova_ceph_client in ceph_client_filtered_clients | map(attribute='name') | list
   changed_when: false
   delegate_to: '{{ ceph_mon_host }}'
   register: ceph_nova_secret