This patch reverts the previous revert.

It seems the outage was caused by the new feature of supporting
`node.kubernetes.io/exclude-from-external-load-balancers`, which was set
on all nodes, resulting in non being used by metallb. Therefore the
upgrade should be fine, it was just an unexpectedly well working feature
that caused the outage.

This patch does a rollback of Metallb after an outage of all
loadbalancer IPs in the cluster without any useful events or error logs.

This reverts commit 6c10ae98.

This patch updates the link to the helm repository for AMD GPU drivers
after AMD changed Github organisation names.

This patch adds a readinessProbe to the quorum pods, this causes the
kubelet to test the etcd health endpoint, resulting in proper status of
the etcd node, and therefore keeping the quorum. This should help to
improve cluster stablility.

Finally got around to fix the kubelet certificate situation. This patch
resolves the outstanding issue with having this flag around.