For kube-proxy, node addition and node update is semantically
considered as similar event, we have exactly same handler
logic for these two events resulting in duplicate code and
unit tests.
This merges the `NodeHandler` interface methods OnNodeAdd and
OnNodeUpdate into OnNodeChange along with the implementation
of the interface.
Signed-off-by: Daman Arora <aroradaman@gmail.com>
46e2c22fd7