Replace tripleo-scenario003-multinode with scenario003-standalone
Replace tripleo-scenario003-multinode with scenario003-standalone

Change-Id: I7692d9409f30d26d051c40cc10e32fa93e9056e8
Story: https://tree.taiga.io/project/tripleo-ci-board/us/533

openstack/python-mistralclient,openstack/python-mistralclient