[analyzer] remove "auto-generated do not edit" comments

pkg/analyzer/lib/src/generated/testing/ast_factory.dart

Index: pkg/analyzer/lib/src/generated/testing/ast_factory.dart
diff --git a/pkg/analyzer/lib/src/generated/testing/ast_factory.dart b/pkg/analyzer/lib/src/generated/testing/ast_factory.dart
index b0702c737ffbd0ae91fa9cf4afd328c01d229d1b..ca45b884f9287ccf4165fc52f2a51ccefa3ef2cf 100644
--- a/pkg/analyzer/lib/src/generated/testing/ast_factory.dart
+++ b/pkg/analyzer/lib/src/generated/testing/ast_factory.dart
@@ -2,9 +2,6 @@
 // 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.
 
-// This code was auto-generated, is not intended to be edited, and is subject to
-// significant change. Please see the README file for more information.
-
 library engine.testing.ast_factory;
 
 import 'package:analyzer/src/generated/ast.dart';