[Fix] Consistency in ButtonStyleButton related Tests (#140610)

[Fix] Consistency in ButtonStyleButton related Tests:
- Replaced the usage of ElevatedButton with FilledButton in FilledButton's test.
- Replaced the usage of TextButton.styleFrom with FilledButton.styleFrom in FilledButton's test.
- Replaced the usage of TextButton.styleFrom with ElevatedButton.styleFrom in ElevatedButton's test.

packages/flutter/test/material/elevated_button_test.dart

@@ -1578,7 +1578,7 @@ void main() {
               children: <Widget>[
                 ElevatedButton(
                   key: key0,
-                  style: TextButton.styleFrom(
+                  style: ElevatedButton.styleFrom(
                     minimumSize: const Size(24, 36),
                     maximumSize: const Size.fromWidth(64),
                   ),
@@ -1587,7 +1587,7 @@ void main() {
                 ),
                 ElevatedButton.icon(
                   key: key1,
-                  style: TextButton.styleFrom(
+                  style: ElevatedButton.styleFrom(
                     minimumSize: const Size(24, 36),
                     maximumSize: const Size.fromWidth(104),
                   ),

packages/flutter/test/material/filled_button_test.dart

@@ -1405,7 +1405,7 @@ void main() {
         theme: ThemeData.from(colorScheme: const ColorScheme.light(), useMaterial3: true),
         home: Scaffold(
                 body: Center(
-                  child: ElevatedButton(
+                  child: FilledButton(
                     key: key,
                     onPressed: () {},
                     child: const Text('FilledButton'),
@@ -1435,7 +1435,7 @@ void main() {
                     key: key,
                     icon: const Icon(Icons.favorite),
                     onPressed: () {},
-                    label: const Text('ElevatedButton'),
+                    label: const Text('FilledButton'),
                   ),
                 ),
               ),
@@ -1652,7 +1652,7 @@ void main() {
               children: <Widget>[
                 FilledButton(
                   key: key0,
-                  style: TextButton.styleFrom(
+                  style: FilledButton.styleFrom(
                     minimumSize: const Size(24, 36),
                     maximumSize: const Size.fromWidth(64),
                   ),
@@ -1661,7 +1661,7 @@ void main() {
                 ),
                 FilledButton.icon(
                   key: key1,
-                  style: TextButton.styleFrom(
+                  style: FilledButton.styleFrom(
                     minimumSize: const Size(24, 36),
                     maximumSize: const Size.fromWidth(104),
                   ),