Revert "fix usage of opportunistic test cases with enginefacade"
Revert "fix usage of opportunistic test cases with enginefacade"

This reverts commit e59f95439b46a243ff4aee277397e17f28f79c45 removing
the unused EngineFacadeFixture class.

The patch that needed this (https://review.openstack.org/#/c/283364/)
was never merged to Nova. We only wanted this in Nova tree as a
temporary workaround for oslo.db limitations. Since then the related
bug in oslo.db was closed - folks are encouraged to use the fixtures
provided by the library:

https://docs.openstack.org/developer/oslo.db/api/oslo_db.sqlalchemy.test_fixtures.html

Related-Bug: #1548960

Change-Id: Ia9792604bb6ef65b9601fb212b2aeca16284b69f

rahulunair/nova,Juniper/nova,mahak/nova,mikalstill/nova,gooddata/openstack-nova,mikalstill/nova,mahak/nova,klmitch/nova,jianghuaw/nova,rajalokan/nova,jianghuaw/nova,klmitch/nova,klmitch/nova,Juniper/nova,vmturbo/nova,rahulunair/nova,rajalokan/nova,openstack/nova,mikalstill/nova,jianghuaw/nova,mahak/nova,rajalokan/nova,vmturbo/nova,Juniper/nova,klmitch/nova,phenoxim/nova,gooddata/openstack-nova,rajalokan/nova,jianghuaw/nova,openstack/nova,phenoxim/nova,vmturbo/nova,Juniper/nova,vmturbo/nova,gooddata/openstack-nova,rahulunair/nova,openstack/nova,gooddata/openstack-nova