Use Tempest-lib's availability_zone_client

availability_zone_client has been migrated to tempest-lib-
I573ca2cf2076bd6c3e0cb9e457f1da2a64c211da

Now Tempest-lib provides this client as stable interface so Tempest
should start using this from lib and remove its own copy.
Also remove other files for this client like response schema, unit tests.

This commits makes Tempest to use availability_zone_client from
Tempest-lib.

Change-Id: Ic5d4b115b7e6702bb57792e58e29b16270ac0f29
5 files changed