Remove uses of the old plugin model from the analysis server

pkg/analysis_server/test/edit/refactoring_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/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
-import 'package:plugin/manager.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 import '../mocks.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ConvertGetterMethodToMethodTest);
     defineReflectiveTests(ConvertMethodToGetterTest);
@@ skipping 726 matching lines @@
 
   Future getRefactoringsForString(String search) {
     int offset = findOffset(search);
     return getRefactorings(offset, search.length);
   }
 
   @override
   void setUp() {
     super.setUp();
     createProject();
-    ExtensionManager manager = new ExtensionManager();
-    manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
     server.handlers = [handler];
   }
 
   Future test_convertMethodToGetter_hasElement() {
     return assertHasKind('''
 int getValue() => 42;
 ''', 'getValue', RefactoringKind.CONVERT_METHOD_TO_GETTER, true);
   }
 
@@ skipping 1161 matching lines @@
             kind, testFile, offset, length, validateOnly,
             options: options)
         .toRequest('0');
     return serverChannel.sendRequest(request);
   }
 
   @override
   void setUp() {
     super.setUp();
     createProject();
-    ExtensionManager manager = new ExtensionManager();
-    manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
     server.handlers = [handler];
   }
 }