Add assertion after domain deletion
Add assertion after domain deletion

This commit adds an assertion to verify the domain is not found in
the list after deletion.

Change-Id: I41fe7f0192632c1700082c72c1db4490aef1a47d
Closes-Bug: 1512597

bigswitch/tempest,cisco-openstack/tempest,sebrandon1/tempest,Juniper/tempest,LIS/lis-tempest,LIS/lis-tempest,masayukig/tempest,vedujoshi/tempest,Tesora/tesora-tempest,bigswitch/tempest,Tesora/tesora-tempest,cisco-openstack/tempest,vedujoshi/tempest,sebrandon1/tempest,openstack/tempest,zsoltdudas/lis-tempest,Juniper/tempest,openstack/tempest,masayukig/tempest,zsoltdudas/lis-tempest