purge-docker-cluste: add a task to check hosts
purge-docker-cluste: add a task to check hosts

It's useful when running on CI to see what might remain on the machines.
So we list all the containers and images. We expect the list to be
empty.

We fail if we see containers running.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

fgal/ceph-ansible,fgal/ceph-ansible,ceph/ceph-ansible,ceph/ceph-ansible