Use Tempest-lib's compute quotas_client

Compute quotas_client has been migrated to
tempest-lib- Ib0fcb82ce09ea68d9899836264e8037ac977347b

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 quotas_client
from Tempest-lib.

Change-Id: Idbe0014ee44a74af02753848d244b8360bb5f9fc
4 files changed