Remove more libraries directives from server

pkg/analysis_server/lib/src/context_manager.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.
 
-library context.directory.manager;
-
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:core';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analyzer/context/context_root.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/plugin/resolver_provider.dart';
@@ skipping 1957 matching lines @@
     }
     return _embedderLocator;
   }
 
   @override
   SdkExtensionFinder getSdkExtensionFinder(ResourceProvider resourceProvider) {
     return _sdkExtensionFinder ??=
         new SdkExtensionFinder(buildPackageMap(resourceProvider));
   }
 }