Initialize RBD pool
Initialize RBD pool

When we deploy devstack, we need to initialize the RBD pool.

Not doing so means that functionality like rbd trash purge
scheduling will not work correctly.

Ref: https://docs.ceph.com/en/latest/start/quick-rbd/
Change-Id: I5b0b3b83fb7ef805929fdcd106a5c8a988b05ec4

openstack/devstack-plugin-ceph