Backport some v3 availability zones API UT to v2 API

This patch adds below v3 availability zones API unittest
into V2 API to improve V2 API unittesting.

Change-Id: Icf5875b68ecde85c044efb1e2b05416de8b0c9db
Merge "Backport some v3 availability zones API UT to v2 API"