Uninstall sometimes gets stuck on cert-manager challenges

[jwietelmann]

What happens:

• A namespace gets stuck in a Terminating state that will never complete
• Because there is a cert-manager Challenge resource in the namespace with a finalizer that will never work

How to figure it out:

function klist() {
  kubectl api-resources --verbs=list --namespaced -o name \
  | xargs -n 1 kubectl get --show-kind --ignore-not-found -n $1
}

Find all of the resources in the stuck namespace with:

klist <namespace>

Probably see a Challenge in there.
Delete it with kubectl.
(It won't actually terminate.)
Edit it to remove the finalizer.
It will terminate, and then so will the namespace.