RC/RS: Use ControllerRef to route watch events.

This is part of the completion of ControllerRef, as described here:

https://github.com/kubernetes/community/blob/master/contributors/design-proposals/controller-ref.md#watches

This also removes the need for the Pod->Controller mapping cache in RC
and RS. This mapping is now persisted in the Pod's ControllerRef
instead.

cmd/kube-controller-manager/app/extensions.go

@@ -63,7 +63,6 @@ func startReplicaSetController(ctx ControllerContext) (bool, error) {
 		ctx.InformerFactory.Core().V1().Pods(),
 		ctx.ClientBuilder.ClientOrDie("replicaset-controller"),
 		replicaset.BurstReplicas,
-		int(ctx.Options.LookupCacheSizeForRS),
 	).Run(int(ctx.Options.ConcurrentRSSyncs), ctx.Stop)
 	return true, nil
 }