Convert domain params tests to requests_mock
Convert domain params tests to requests_mock

We still have places using client method mocking. Remove them.

Change-Id: I34fbc19aca4b6514215ed497117c635fa810473d

dtroyer/python-openstacksdk,stackforge/python-openstacksdk,openstack/python-openstacksdk,dtroyer/python-openstacksdk,stackforge/python-openstacksdk,openstack/python-openstacksdk