This migrates the above files from tempest. This includes tempest commits:
* server_groups_client.py : Icb38fd22c61545cfbe024108a06068ada01afc6b
* test_server_groups_client.py: I3ad6761651cec5e66012d08e6b63322f53286a5c
* servers.py : Ica929c402a3d042ae751302384e68853eb28b405
Partially implements blueprint migrate-service-clients-to-tempest-lib
to see the commit history for these files refer to the above Change-Ids in the tempest repository
Change-Id: Ie95fcbfad5352d272e8977c33f80ebb9769fe824