Allow-List of supported k8s kinds should be used only when applying labels

The `imageReplacer`'s role is to replace image names in k8s yaml by fully qualified names. It does that by visiting the k8s resources, looking for `image` fields and replacing image names that it has a fully qualified name for.

Since #3833, we have an Allow-List that specifies which resource kinds can be transformed and we lost the possibility to replace `image` fields in any random Custom Resource. This was mainly introduced to stop applying labels to resources that had a `metadata` field but didn't support `metadata/labels`.

I think we went to far with that Allow-List and that it **should apply only when we set labels on resources**. (Which by the way we might stop doing)

Another case that we have broken is that we collect namespaces only on resources whose kind is in the Allow-List.