Fixed ThemeData in the Flutter Samples unnecessarily includes useMaterial3 = true (Issue #2214) (#2217)

experimental/federated_plugin/federated_plugin/example/lib/main.dart

@@ -15,7 +15,7 @@ class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      theme: ThemeData.light(useMaterial3: true),
+      theme: ThemeData.light(),
       home: const HomePage(),
     );
   }

experimental/linting_tool/lib/theme/app_theme.dart

@@ -9,7 +9,7 @@ import 'package:linting_tool/theme/colors.dart';
 
 abstract class AppTheme {
   static ThemeData buildReplyLightTheme(BuildContext context) {
-    final base = ThemeData.light(useMaterial3: true);
+    final base = ThemeData.light();
     return base.copyWith(
       bottomSheetTheme: BottomSheetThemeData(
         backgroundColor: AppColors.blue700,

experimental/pedometer/example/lib/main.dart

@@ -17,7 +17,6 @@ class MyApp extends StatelessWidget {
       title: 'Flutter Demo',
       theme: ThemeData(
         primarySwatch: Colors.blue,
-        useMaterial3: true,
       ),
       home: const Home(),
     );

experimental/varfont_shader_puzzle/lib/main.dart

@@ -19,7 +19,6 @@ class TypePuzzle extends StatelessWidget {
       title: 'Type Jam',
       theme: ThemeData(
         primarySwatch: Colors.grey,
-        useMaterial3: true,
       ),
       home: const Scaffold(
         appBar: null,

experimental/web_dashboard/lib/src/app.dart

@@ -66,7 +66,7 @@ class _DashboardAppState extends State<DashboardApp> {
     return Provider.value(
       value: _appState,
       child: MaterialApp(
-        theme: ThemeData.light(useMaterial3: true),
+        theme: ThemeData.light(),
         home: SignInSwitcher(
           appState: _appState,
           apiBuilder: widget.apiBuilder,