Fix Slider renders track when track colors are transparent (#161814)
### Description
Fixes [`Slider` with transparent track colors and custom `trackHeight`
cannot reach the extreme ends
](https://github.com/flutter/flutter/issues/161210)
### 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 StatefulWidget {
const MyApp({super.key});
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
double _value = 0;
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: Column(
spacing: 20,
mainAxisSize: MainAxisSize.min,
children: [
SizedBox(
height: 4,
width: 400,
child: DecoratedBox(
decoration: const BoxDecoration(
gradient:
LinearGradient(colors: [Colors.yellow, Colors.green]),
),
child: SliderTheme(
data: const SliderThemeData(
trackHeight: 200,
activeTrackColor: Colors.transparent,
inactiveTrackColor: Colors.transparent,
padding: EdgeInsets.zero,
),
child: Slider(
value: _value,
max: 100,
onChanged: (double value) {
setState(() {
_value = value;
});
},
),
),
),
),
Text('Slider value: ${_value.roundToDouble()}')
],
),
),
),
);
}
}
```
</details>
### Before
<img width="728" alt="Screenshot 2025-01-17 at 16 32 00"
src="https://github.com/user-attachments/assets/378a31b2-b897-4bf8-9067-66539239af09"
/>
### After
<img width="728" alt="Screenshot 2025-01-17 at 16 31 33"
src="https://github.com/user-attachments/assets/aef12d5e-a0cc-4947-8f72-2024edf29f14"
/>
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there for submitting PRs.
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responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.
If you need help, consider asking for advice on the #hackers-new channel
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[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
58b7ee137e