Automatic merge from submit-queue
kubectl: show node label if defined
We are moving towards marking master nodes as tainted, and not
necessarily unschedulable. Further now we encourage users to taint
nodes, marking them unschedulable.
Thus the reliance on "Unschedulable" is not really a great indicator for
the master.
Instead, recognize the existing node 'role' markers, and surface them
where Unschedulable is (in the status).
We recognize:
* a kubernetes.io/role label
* a kubeadm.alpha.kubernetes.io/role label
~a taint with Key 'dedicated'~
Fix#33533