Use Tempest-lib's compute services_client

Compute services_client has been migrated to
tempest-lib- I29684ec61023650bd2bb3a76b708bac24608f6c0

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 commit makes Tempest to use compute services_client
from Tempest-lib.

Change-Id: I7498e25136ad790cec158d5b654dbbdbd8146753
5 files changed