Don't evaluate extra nodes if there's no score plugin defined

pkg/scheduler/framework/extender.go

@@ -50,6 +50,9 @@ type Extender interface {
 	// this pod is managed by this extender.
 	IsInterested(pod *v1.Pod) bool
 
+	// IsPrioritizer returns whether this extender is configured for the Prioritize method.
+	IsPrioritizer() bool
+
 	// ProcessPreemption returns nodes with their victim pods processed by extender based on
 	// given:
 	//   1. Pod to schedule