fix: remove another file that shouldn't be in source

examples/flutter-user-management/lib/generated_plugin_registrant.dart

@@ -1,19 +0,0 @@
-//
-// Generated file. Do not edit.
-//
-
-// ignore_for_file: lines_longer_than_80_chars
-
-import 'package:image_picker_for_web/image_picker_for_web.dart';
-import 'package:uni_links_web/uni_links_web.dart';
-import 'package:url_launcher_web/url_launcher_web.dart';
-
-import 'package:flutter_web_plugins/flutter_web_plugins.dart';
-
-// ignore: public_member_api_docs
-void registerPlugins(Registrar registrar) {
-  ImagePickerPlugin.registerWith(registrar);
-  UniLinksPlugin.registerWith(registrar);
-  UrlLauncherPlugin.registerWith(registrar);
-  registrar.registerMessageHandler();
-}