Launch ironic-multitest post_test_hook from stack user
Launch ironic-multitest post_test_hook from stack user

This patch updates post_test_hook to call exercise.sh script from
stack user.

Change-Id: Ib04055efe9124e02debece4f4d9df62337d08506

openstack-infra/project-config,Tesora/tesora-project-config,Tesora/tesora-project-config,openstack-infra/project-config