Fix DeprecationWarning in test_volume_pools.py

This commit fixes the DeprecationWarning in test_volume_pools.py. And
this commit also fixes the wrong method name 'show_pools()' to
'list_pools()' in the warning message.

Change-Id: Ia07e1339ab178e2de8873506194129b6cc65b7b0
2 files changed