Skip multi availability zones test when there is a single az

Fix a misbehavior in a tempest test created to run with multiple
availability zones. This test was not being skipped in environments
with a single availability zone that contains two pools. Now, even
if there are two available pools, this test is going to be skipped.

Change-Id: Ic2012e6ecb334daa2ac97058cade0eadfe0a88be
Closes-Bug: #1878055
1 file changed