refactor(tests): replace 'final' with 'const' for improved performance in various test files

test/features/blog_post_create/presentation/pages/blog_post_create_screen_test.dart

@@ -57,7 +57,7 @@ void main() {
         routes: [
           GoRoute(
             path: '/home',
-            builder: (context, state) => Scaffold(
+            builder: (context, state) => const Scaffold(
               body: Center(child: Text('Home')),
             ),
           ),
@@ -81,7 +81,7 @@ void main() {
       return MaterialApp.router(
         routerConfig: router,
         theme: ThemeHelper().themeData(),
-        localizationsDelegates: [
+        localizationsDelegates: const [
           S.delegate,
           GlobalMaterialLocalizations.delegate,
           GlobalWidgetsLocalizations.delegate,