Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/analysis/notification_overrides_test.dart

Index: pkg/analysis_server/test/analysis/notification_overrides_test.dart
diff --git a/pkg/analysis_server/test/analysis/notification_overrides_test.dart b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
index 61db5131d965aab71e8a917b83c33d2620912377..750c6b83dd4aa61f790e946894de4fbd035e8b38 100644
--- a/pkg/analysis_server/test/analysis/notification_overrides_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
@@ -8,15 +8,17 @@ import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/constants.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../analysis_abstract.dart';
 import '../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(AnalysisNotificationOverridesTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(AnalysisNotificationOverridesTest);
+  });
 }
 
 @reflectiveTest