Right now we only keep in Harbor the latest 10 images for Toolforge components. The older images are automatically cleaned up.
If we push many test images, we sometimes end up deleting the image that is currently running in production (the one specified in the toolforge-deploy repo).
We should find a way to prevent this from happening, because otherwise we get in a situation where k8s is not able to download the image for a component, and we only rely on it being cached on the k8s workers.
We used to have "immutable" tags that were never deleted, but that is also problematic because it means we fill up Harbor with images that were previously deployed but are no longer needed. Related previous task: T348538: [tools,harbor] Cleanup old production images