[cern] enable cvmfs in swarm mode

setup docker-volume-cvmfs in all nodes, including the master nodes. swarm mode schedules services and containers in any of the manager or workers, so we should enable it everywhere.

Closes #4411

magnum/drivers/common/templates/fragments/configure-cvmfs.sh

@@ -10,7 +10,7 @@ chattr -i /
 mkdir /cvmfs
 chattr +i /
 
-atomic install gitlab-registry.cern.ch/cloud-infrastructure/docker-volume-cvmfs:${CVMFS_TAG}
+atomic install gitlab-registry.cern.ch/cloud-infrastructure/docker-volume-cvmfs:${CVMFS_TAG:-latest}
 
 # add selinux policy
 docker cp docker-volume-cvmfs:/dockercvmfs.pp /tmp