Draft: Repair cluster-build pipeline

The introduction of building RHEL8 images on the cluster in MR !1681 (merged) had a flaw: it would recreate image streams on every CI run, thereby losing the association to images in the image registry. In the CI, we change from time to time the ran-base image between tags develop and ci-temp. By recreating the image streams, we quickly lost the association of ran-base:develop, which the CI assumed to "just be there". In this case, most builds would fail, basically bringing the CI to a halt. The actually important change here is in 83736340

Marking as BUILD-ONLY as we cannot test this in the CI: the CI will trigger the normal RHEL8 build on asterix. I will reproduce the scenario we had previously, i.e., trigger this pipeline multiple times in a way that builds will change the ran-base image between ran-base:develop and ran-base:ci-temp. The expected outcome is to always have a successful build, of course.

@lthomas I have additional changes to not use the SSHConnection class, but this will come later. The same with the cleanup of the physims.

ci-scripts/cls_cluster.py

@@ -134,7 +134,7 @@ class Cluster:
 		while timeout_sec > 0:
 			# check status
 			for j in jobs:
-				sshSession.command(f'oc get pods | grep {j}', '\$', 5, silent = True)
+				sshSession.command(f'oc get pods | grep {j}', '\$', 10, silent = True)
 				if sshSession.getBefore().count('Completed') > 0: jobs.remove(j)
 				if sshSession.getBefore().count('Error') > 0:
 					logging.error(f'error for job {j}: ' + sshSession.getBefore())