fixes [`ExpansionTile` properties aren't updated with `setState`](https://github.com/flutter/flutter/issues/24493)

### Code sample

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Example(),
    );
  }
}

class Example extends StatefulWidget {
  const Example({super.key});

  @override
  State<Example> createState() => _ExampleState();
}

class _ExampleState extends State<Example> {
  ShapeBorder collapsedShape = const RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(4)),
  );
  Color collapsedTextColor = const Color(0xffffffff);
  Color collapsedBackgroundColor = const Color(0xffff0000);
  Color collapsedIconColor = const Color(0xffffffff);
  ShapeBorder shape = const RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(16)),
  );
  Color backgroundColor = const Color(0xffff0000);
  Color textColor = const Color(0xffffffff);
  Color iconColor = const Color(0xffffffff);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ExpansionTile(
                shape: shape,
                backgroundColor: backgroundColor,
                textColor: textColor,
                iconColor: iconColor,
                collapsedShape: collapsedShape,
                collapsedTextColor: collapsedTextColor,
                collapsedBackgroundColor: collapsedBackgroundColor,
                collapsedIconColor: collapsedIconColor,
                title: const Text('Collapsed ExpansionTile'),
                children: const [
                  ListTile(
                    title: Text('Revealed!'),
                  ),
                ],
              ),
              const SizedBox(height: 16),
              ExpansionTile(
                shape: shape,
                backgroundColor: backgroundColor,
                textColor: textColor,
                iconColor: iconColor,
                initiallyExpanded: true,
                title: const Text('Expanded ExpansionTile'),
                children: const [
                  ListTile(
                    title: Text('Revealed!'),
                  ),
                ],
              ),
              const SizedBox(height: 16),
              FilledButton(
                onPressed: () {
                  setState(() {
                    collapsedShape = const RoundedRectangleBorder(
                      borderRadius: BorderRadius.all(Radius.circular(50)),
                    );
                    collapsedTextColor = const Color(0xfff00000);
                    collapsedBackgroundColor = const Color(0xffffff00);
                    collapsedIconColor = const Color(0xfff00000);

                    shape = const RoundedRectangleBorder();
                    backgroundColor = const Color(0xfffff000);
                    textColor = const Color(0xfff00000);
                    iconColor = const Color(0xfff00000);
                  });
                },
                child: const Text('Update properties'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}
```

</details> 

### Before

https://github.com/flutter/flutter/assets/48603081/b29aed98-38ff-40a3-9ed3-c4342ada35b6

### After

https://github.com/flutter/flutter/assets/48603081/5e0b6a34-c577-40ed-8456-7ef55caa277b