Add IncrementClusterEventType function to metrics interface (#8728)

einterfaces/metrics.go

@@ -20,6 +20,7 @@ type MetricsInterface interface {
 
 	IncrementClusterRequest()
 	ObserveClusterRequestDuration(elapsed float64)
+	IncrementClusterEventType(eventType string)
 
 	IncrementLogin()
 	IncrementLoginFail()