system-cluster-critical priorityClass is not permitted in default namespace

[nkinkade]

I noticed this warning in GKE in mlab-oti while doing something else:

pods "kubeip-7545b86569-" is forbidden: pods with system-cluster-critical priorityClass is not permitted in default namespace

And I see that indeed the podSpec for kubeip defines priorityClassName: system-cluster-critical.

We should either remove the priorityClass (is it necessary?), or move it to the kube-system namespace:

doitintl/kubeip#39