Following up on OSASINFRA-2681, instrument the tests to be run on all e2e-openstack workflows.

Possibly:

• create a new step `openshift-e2e-openstack-test` that runs the new openstack tests
• create a chain that contains both openshift-e2e-test and openshift-e2e-openstack-test (possibly, `openshift-e2e-openstack-test`)
• in all e2e-openstack workflows, replace`ref: openshift-e2e-test` with `chain: openshift-e2e-openstack-test` in the `test` stanza.

Expected outcome:

• the test step runs and succeeds (among other things, an appropriate image is needed)
• the test results are presented in Prow in a readable way

It is unclear to me at present how Prow will collect xunit test results from two separate test steps; sorting out this one might be needed in order to get readable results.