Automatic merge from submit-queue
NodeController doesn't evict Pods if no Nodes are Ready
Fix#13412#24597
When NodeControllers don't see any Ready Node it goes into "network segmentation mode". In this mode it cancels all evictions and don't evict any Pods.
It leaves network segmentation mode when it sees at least one Ready Node. When leaving it resets all timers, so each Node has full grace period to reconnect to the cluster.
cc @lavalamp @davidopp @mml @wojtek-t @fgrzadkowski