PR CI checks running OpenShift integration tests are executed internally

[fabiobrz]

Integration tests on OpenShift are no longer run via the OpenShift org Prow jobs, because of new policies affecting cluster pools availability, see https://docs.ci.openshift.org/docs/how-tos/cluster-claim/#existing-cluster-pools 🙁

The cluster pools owned by openshift-ci are for OpenShift workloads, maintained by DPTP, and they can be used by any tests in the openshift org. Pools with different owners should be used only with knowledge and approval of their owner. 

For this reason we're implementing a new workflow that will use Red Hat internal resources to execute integration tests against managed OpenShift clusters 🎉

While this is being done, Intersmash maintainers will run PRs CI validation jobs manually. 💪

[fabiobrz]

Update: we've implemented a workflow that allows for Intersmash maintainers to trigger CI checks running the integration tests on OpenShift internally.
The automation will produce a comment that will report the output of the checks, see an example here.

We're working on making this even more user friendly, e.g.: by setting a check status and share as much information about failures as possible, but in the meantime we have something working 🙂