By labelling the PersistentVolumeClaim with `group: test`, the label
selector in the VolumeGroupSnapshot will create a snapshot of an RBD
group containing the single volume (or more if there are other volumes
in the same namespace with that label).
Once the VolumeGroupSnapshot is created, each volume in the group will
have a VolumeSnapshot that can be restored.
Signed-off-by: Niels de Vos <ndevos@ibm.com>