Disable a test that times out on the bots

pkg/analysis_server/test/integration/server/set_subscriptions_test.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 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ skipping 49 matching lines @@
   }
 }
 
 @reflectiveTest
 class SetSubscriptionsTest extends AbstractSetSubscriptionsTest {}
 
 @reflectiveTest
 class SetSubscriptionsTest_Driver extends AbstractSetSubscriptionsTest {
   @override
   bool get enableNewAnalysisDriver => true;
+
+  @failingTest
+  @override
+  test_setSubscriptions() {
+    // This test times out on the bots and has been disabled to keep them green.
+    // We need to discover the cause and re-enable it.
+    fail('Timed out');
+  }
 }