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
diff --git a/tempest/clients.py b/tempest/clients.py
index 276f7eb..c545f94 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -18,6 +18,8 @@
 from oslo_log import log as logging
 from tempest_lib.services.compute.agents_client import AgentsClient
 from tempest_lib.services.compute.aggregates_client import AggregatesClient
+from tempest_lib.services.compute.availability_zone_client import \
+    AvailabilityZoneClient
 from tempest_lib.services.identity.v2.token_client import TokenClient
 from tempest_lib.services.identity.v3.token_client import V3TokenClient
 
@@ -29,8 +31,6 @@
 from tempest.services.baremetal.v1.json.baremetal_client import \
     BaremetalClient
 from tempest.services import botoclients
-from tempest.services.compute.json.availability_zone_client import \
-    AvailabilityZoneClient
 from tempest.services.compute.json.baremetal_nodes_client import \
     BaremetalNodesClient
 from tempest.services.compute.json.certificates_client import \