Remove unnecessary DEBUG log while removing a pod from the cache

	n, ok := cache.nodesMap[pod.Spec.NodeName]
	if !ok {
		return fmt.Errorf("node %v is not found", pod.Spec.NodeName)
	}
	if err := n.RemovePod(pod); err != nil {
		return err
	}

It can causes DEBUG log("node is not found") if node name is an empty string. For example: the pod status is updated (according to outstanding requests) before it is assumed to be run on a node.