Move diagnostics to `diagnostics` domain (#24931).

pkg/analysis_server/test/test_all.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:unittest/unittest.dart';
 
 import 'analysis/test_all.dart' as analysis_all;
 import 'analysis_server_test.dart' as analysis_server_test;
 import 'channel/test_all.dart' as channel_test;
 import 'context_manager_test.dart' as context_manager_test;
 import 'domain_analysis_test.dart' as domain_analysis_test;
 import 'domain_completion_test.dart' as domain_completion_test;
+import 'domain_diagnostic_test.dart' as domain_experimental_test;
 import 'domain_execution_test.dart' as domain_execution_test;
-import 'domain_experimental_test.dart' as domain_experimental_test;
 import 'domain_server_test.dart' as domain_server_test;
 import 'edit/test_all.dart' as edit_all;
 import 'operation/test_all.dart' as operation_test_all;
 import 'plugin/test_all.dart' as plugin_all;
 import 'protocol_server_test.dart' as protocol_server_test;
 import 'protocol_test.dart' as protocol_test;
 import 'search/test_all.dart' as search_all;
 import 'server_options_test.dart' as server_options;
 import 'services/test_all.dart' as services_all;
 import 'socket_server_test.dart' as socket_server_test;
@@ skipping 22 matching lines @@
     protocol_server_test.main();
     protocol_test.main();
     search_all.main();
     server_options.main();
     services_all.main();
     socket_server_test.main();
     source_all.main();
     src_all.main();
   });
 }