fixes [The InputDecoration's suffix and prefix widget can be tapped even if it does not appear](https://github.com/flutter/flutter/issues/139916)

This PR also updates two existing tests to pass the tests for this PR. These tests are trying to tap prefix and  suffix widgets when they're hidden. While the linked issue had visible prefix and suffix widgets https://github.com/flutter/flutter/issues/39376 for reproduction.

### Code sample

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

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

void main() {
  runApp(MainApp());
}

class MainApp extends StatelessWidget {
  final _messangerKey = GlobalKey<ScaffoldMessengerState>();

  MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      scaffoldMessengerKey: _messangerKey,
      home: Scaffold(
        body: Container(
          alignment: Alignment.center,
          padding: const EdgeInsets.all(16.0),
          child: TextField(
            decoration: InputDecoration(
              labelText: 'Something',
              prefix: GestureDetector(
                onTap: () {
                  _messangerKey.currentState?.showSnackBar(
                      const SnackBar(content: Text('A tap has occurred')));
                },
                child: const Icon(Icons.search),
              ),
              suffix: GestureDetector(
                onTap: () {
                  _messangerKey.currentState?.showSnackBar(
                      const SnackBar(content: Text('A tap has occurred')));
                },
                child: const Icon(Icons.search),
              ),
            ),
          ),
        ),
      ),
    );
  }
}
```

</details>

### Before
![ScreenRecording2024-02-12at18 40 34-ezgif com-video-to-gif-converter](https://github.com/flutter/flutter/assets/48603081/c101e0d6-ce5a-4b28-9626-28bcb83d2a5c)

### After
![ScreenRecording2024-02-12at18 40 10-ezgif com-video-to-gif-converter](https://github.com/flutter/flutter/assets/48603081/923b348e-8adf-4d64-9dc3-e75d30e3e2fb)