Use Tempest-lib's compute server_groups_client

Compute server_groups_client has been migrated to
tempest-lib- Ie95fcbfad5352d272e8977c33f80ebb9769fe824

Now Tempest-lib provides this client as stable interface so Tempest
should start using this from lib and remove its own copy.
Also remove its unit tests.

This commits makes Tempest to use compute server_groups_client
from Tempest-lib.

NOTE- There are difference between migrated files and current tempest file
- I3abac40ebb33836980c119d59bc97f035b213c0a
- I75307176c2f032301da6227249070c42af54dd6e
But those are already taken care in lib.

Change-Id: Ia79db7d9065cad3f21f2bf32b97710438ecaa349
diff --git a/tempest/clients.py b/tempest/clients.py
index a5f51c3..74c8dcd 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -55,6 +55,8 @@
     SecurityGroupRulesClient
 from tempest_lib.services.compute.security_groups_client import \
     SecurityGroupsClient as ComputeSecurityGroupsClient
+from tempest_lib.services.compute.server_groups_client import \
+    ServerGroupsClient
 from tempest_lib.services.compute.services_client import ServicesClient
 from tempest_lib.services.compute.snapshots_client import \
     SnapshotsClient as ComputeSnapshotsClient
@@ -75,8 +77,6 @@
 from tempest.services.baremetal.v1.json.baremetal_client import \
     BaremetalClient
 from tempest.services.compute.json.keypairs_client import KeyPairsClient
-from tempest.services.compute.json.server_groups_client import \
-    ServerGroupsClient
 from tempest.services.compute.json.servers_client import ServersClient
 from tempest.services.data_processing.v1_1.data_processing_client import \
     DataProcessingClient