Minor improvement in test_user_id_persistence
Minor improvement in test_user_id_persistence

Added a validation via the identity_api: there is indeed a user stored
in the backend.

Change-Id: Ie05e88cfadbf64ac7b82279ad80c88b2c02cee17

ilay09/keystone,rajalokan/keystone,ilay09/keystone,openstack/keystone,openstack/keystone,mahak/keystone,mahak/keystone,mahak/keystone,openstack/keystone,rajalokan/keystone,ilay09/keystone,rajalokan/keystone