Thinking about this we also need a scenario upstream in TripleO CI that runs through the multiattach tests as seen in Nova CI below: https://github.com/openstack/nova/blob/318d353d6479d4af13822d4fd0cde2a5c3790762/.zuul.yaml#L88-L102 https://github.com/openstack/tempest/blob/1068f8b77556b0a8871915f6c80c91fd3f856f3c/tempest/api/compute/volumes/test_attach_volume.py#L269-LL440
Closing as NOTABUG after verifying that an OSP 13 TripleO deployed env has the required policy changes in place to allow multiattach to work.