Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/completion/test_all.dart

Index: pkg/analysis_server/test/services/completion/test_all.dart
diff --git a/pkg/analysis_server/test/services/completion/test_all.dart b/pkg/analysis_server/test/services/completion/test_all.dart
index f219ddaac6a2106824c96369867be21dbd63d310..d6b2b9f0026a6655a3edca26ff43972bedee6279 100644
--- a/pkg/analysis_server/test/services/completion/test_all.dart
+++ b/pkg/analysis_server/test/services/completion/test_all.dart
@@ -4,7 +4,7 @@
 
 library test.services.completion;
 
-import 'package:unittest/unittest.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../../utils.dart';
 import 'completion_target_test.dart' as completion_target_test;
@@ -13,8 +13,8 @@ import 'dart/test_all.dart' as dart_contributor_tests;
 /// Utility for manually running all tests.
 main() {
   initializeTestEnvironment();
-  group('completion', () {
+  defineReflectiveSuite(() {
     completion_target_test.main();
     dart_contributor_tests.main();
-  });
+  }, name: 'completion');
 }