Update Ceph version on CI job

Job cinderlib-ceph-functional is using Ceph Luminous, which has been EOL
since March 2020.

This patch updates the job to use an active release, Ceph Pacific.

In the new container they no longer automatically create the rbd pool,
so the patch also updates the playbook to create the pool.

Change-Id: I09a2a9b07ed8b6d994485079febd0bd0190aa6c9

playbooks/setup-ceph.yaml

@@ -61,7 +61,7 @@
           --net=host
           --volume /etc/ceph:/etc/ceph
           --privileged
-          ceph/daemon:latest-luminous
+          ceph/daemon:latest-pacific
           demo
 
       - name: Wait for ceph.conf
@@ -87,5 +87,9 @@
             path: /etc/ceph/ceph.client.admin.keyring
             mode: 0644
 
+      - name: Create rbd pool
+        command: |
+          docker exec ceph-demo ceph osd pool create rbd 8
+
       - shell: cat /etc/ceph/ceph.conf
         register: ceph_conf