Remove uses of the old plugin model from the analysis server

pkg/analysis_server/test/edit/refactoring_test.dart

Index: pkg/analysis_server/test/edit/refactoring_test.dart
diff --git a/pkg/analysis_server/test/edit/refactoring_test.dart b/pkg/analysis_server/test/edit/refactoring_test.dart
index 6c84f579e6b9e60b671c49ec38bb7dae7ef35ce8..b48a9c7d86b1d339278b12be88dc16f487b2b520 100644
--- a/pkg/analysis_server/test/edit/refactoring_test.dart
+++ b/pkg/analysis_server/test/edit/refactoring_test.dart
@@ -8,7 +8,6 @@ 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';
 
@@ -755,8 +754,6 @@ class GetAvailableRefactoringsTest extends AbstractAnalysisTest {
   void setUp() {
     super.setUp();
     createProject();
-    ExtensionManager manager = new ExtensionManager();
-    manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
     server.handlers = [handler];
   }
@@ -1938,8 +1935,6 @@ class _AbstractGetRefactoring_Test extends AbstractAnalysisTest {
   void setUp() {
     super.setUp();
     createProject();
-    ExtensionManager manager = new ExtensionManager();
-    manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
     server.handlers = [handler];
   }