Return complete resp from server_groups_client

Currently compute server_groups_client returns Response by
removing top key from Response.
For example-
 return service_client.ResponseBody(resp, body['server_group'])

As service clients are in direction to move to Tempest-lib, all
service clients should return Response without any truncation.
One good example is Resource pagination links which are lost with current
way of return value. Resource pagination links are present in parallel
(not inside) to top key of Response.

This patch makes compute server_groups_client to return
complete Response body.

Change-Id: I18c2f30558c32eacc65bb012fffa1e8fa94fa1c3
Implements: blueprint method-return-value-and-move-service-clients-to-lib
5 files changed