review cern-magnum gitlab-ci

There are a couple issues we need to improve.

• using docker-priviled-xl: these runners are going away, move to simple k8s based runners (defaul)
• helm job does a dep update: this is an issue right now since we're pushing the chart deps (it's overriding them). it wouldn't be an issue if we wouldn't do that
• move to oci: and a bigger issue... how do we handle the old releases if chartmuseum goes away?

For this release (Q3-2023) i generated the package manually and uploaded it manually as well to the registry under kubernetes/releases (helm charts).

RELEASE_NAME="cern-magnum"
RELEASE_NAMESPACE="kube-system"
helm --namespace "${RELEASE_NAMESPACE}" template -f values-crds.yaml "${RELEASE_NAME}" .         | yq e 'select(.kind == "CustomResourceDefinition")' -         > crds/generated.yaml
helm package .

And then manually uploaded the file.