Remove  RBAC test_volume_list_image_metadata test case

Remove the test_volume_list_image_metadata test case as it duplicates with
test_list_volumes_details_image_metadata in test_volume_metadata_rbac.py.  Also,
test_volume_list_image_metadata does not test list image metadata correctly
since the volume_image_metadata attribute has never been created in the first
place.

Change-Id: I07c3971f5bdb4255105612538e58c79d69daa691
1 file changed