fix the tempest failure for external ceph
fix the tempest failure for external ceph

show_multiple_locations is missing for external ceph, and it will
cause tempest run failed.
it means the conditon for show_multiple_locations is
glance_backend_ceph but not enable_ceph, this patch it fix it.

Change-Id: I3c95c3b0a7e34639b376bdfd0205f3930b06e2cd
Closes-Bug: #1741022
Co-Authored-By: chenqiaomin <5af2fdc3a611123d7b3883beea1bf37b936a4899@99cloud.net>

dardelean/kolla-ansible,dardelean/kolla-ansible,dardelean/kolla-ansible