Add missing flag stanza

Fixes: 378504247
Test: NotificationAssistantsTest
Flag: android.app.notification_classification_ui
Change-Id: If500279ce2ee2fdffcde63b522ca1f625fef1e4e
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/NotificationAssistantsTest.java b/services/tests/uiservicestests/src/com/android/server/notification/NotificationAssistantsTest.java
index 6eb2f71..9eddcc9 100644
--- a/services/tests/uiservicestests/src/com/android/server/notification/NotificationAssistantsTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/NotificationAssistantsTest.java
@@ -720,6 +720,7 @@
     }
 
     @Test
+    @EnableFlags(android.service.notification.Flags.FLAG_NOTIFICATION_CLASSIFICATION)
     public void testDefaultAllowedKeyAdjustments_readWriteXml() throws Exception {
         mAssistants.loadDefaultsFromConfig(true);