Use consistent group metric name for UNI Status PM

Change-Id: Icf7714c4d390901ba4b63d5d4d952b9c65fd4b59
diff --git a/internal/pkg/onuadaptercore/onu_metrics_manager.go b/internal/pkg/onuadaptercore/onu_metrics_manager.go
index 7d2e787..b8860cb 100644
--- a/internal/pkg/onuadaptercore/onu_metrics_manager.go
+++ b/internal/pkg/onuadaptercore/onu_metrics_manager.go
@@ -721,7 +721,7 @@
 
 	raisedTs := time.Now().Unix()
 	mmd := voltha.MetricMetaData{
-		Title:           "UniStatus", // Is this ok to hard code?
+		Title:           UniStatusGroupMetricName,
 		Ts:              float64(raisedTs),
 		Context:         metricsContext,
 		DeviceId:        mm.pDeviceHandler.deviceID,