Previously provisionerPriorityClassName config is applied to node plugin
but pluginPriorityClassName is applied to controller plugin. This causes
a misconfiguration since the default values for
provisionerPriorityClassName is system-cluster-critical and
pluginPriorityClassName is system-node-critical.
The default priority for node plugin ought to be system-node-critical so
we can leverage this information to kill the pods in this priority last,
allowing other pods that may mount RBD-backed volume to unmount cleanly
first, otherwise the shutdown sequence may hang due to failure
unmounting RBD-backed volume when the node plugin pod is already killed.
Signed-off-by: Sonny Sasaka <sonnysasaka@gmail.com>