fixing issues with restarting alarm manager during onu reboot or delete device

Change-Id: I68bdf8318b4502e1fe324acf686c98f3eb356f91
diff --git a/internal/pkg/onuadaptercore/openonu.go b/internal/pkg/onuadaptercore/openonu.go
index 71a9034..b116686 100644
--- a/internal/pkg/onuadaptercore/openonu.go
+++ b/internal/pkg/onuadaptercore/openonu.go
@@ -392,7 +392,8 @@
 		if err := handler.deleteDevicePersistencyData(ctx); err != nil {
 			errorsList = append(errorsList, err)
 		}
-		handler.stopCollector <- true // stop the metric collector routine
+		handler.stopCollector <- true    // stop the metric collector routine
+		handler.stopAlarmManager <- true //stop the alarm manager.
 		if handler.pOnuMetricsMgr != nil {
 			if err := handler.pOnuMetricsMgr.clearAllPmData(ctx); err != nil {
 				errorsList = append(errorsList, err)