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

@@ -348,7 +348,8 @@ class Cluster:
 		build_log_name = f'build_log_{self.testCase_id}'
 		cls_containerize.CopyLogsToExecutor(mySSH, lSourcePath, build_log_name, lIpAddr, 'oaicicd', CONST.CI_NO_PASSWORD)
 
-		mySSH.command(f'oc get images | grep -e \'{"\|".join(attemptedImages)}\' > {build_log_name}/image_registry.log', '\$', 10);
+		grep_exp = "\|".join(attemptedImages)
+		mySSH.command(f'oc get images | grep -e \'{grep_exp}\' > {build_log_name}/image_registry.log', '\$', 10);
 
 		mySSH.command('for pod in $(oc get pods | tail -n +2 | awk \'{print $1}\'); do oc delete pod ${pod}; done', '\$', 60)