Use servers_client from tempest-lib

The files below have been migrated to tempest-lib

 * servers_client.py: I9234f063a72bd58100bfffd3db38718a257ce6ea
 * servers.py: I9234f063a72bd58100bfffd3db38718a257ce6ea
 * test_servers_client.py: I9234f063a72bd58100bfffd3db38718a257ce6ea
 * parameter_types.py: I5cad7d45b3be330ebcfb063315ff29b06cf0688c

Now Tempest-lib provides those as stable interfaces. So Tempest should
start using those from lib and remove its own copy.

Change-Id: Iec56aee243106f8dd79dbf464080dc1382866f07
7 files changed