remove codesign.dart (#78764)

dev/bots/codesign.dart

-// Copyright 2014 The Flutter Authors. 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:io' as io;
-import 'package:path/path.dart' as path;
-
-// TODO(fujino): delete this script once PR #71244 lands on stable.
-void main(List<String> args) {
-  final String scriptPath = io.Platform.script.toFilePath();
-  final String scriptDir = path.dirname(scriptPath);
-  final String repoRoot = path.normalize(path.join(scriptDir, '..', '..'));
-  final io.ProcessResult result = io.Process.runSync(
-    path.join(repoRoot, 'dev', 'tools', 'bin', 'conductor'),
-    <String>['codesign', '--verify'],
-  );
-  if (result.exitCode != 0) {
-    print('codesign script exited with code $result.exitCode');
-    print('stdout:\n${result.stdout}\n');
-    print('stderr:\n${result.stderr}\n');
-    io.exit(1);
-  }
-  print('codesign script succeeded.');
-  print('stdout:\n${result.stdout}');
-}