Release Environment - Automation to rebuild images of old stable branches

In #20119 (closed), we see that the only problem blocking us from deploying old stable branches to release environments is the retention policy for the images. To fix that, we need to rebuild the images. The steps can be done manually as specified in this comment #20119 (comment 1901090166). Of course, we should automate this step, if we want to use RE to validate old stable branches.

Exit Criteria

• CNG images are recreated if they were not available, so new Helm upgrades to Release Environments always start with existing images.