…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ng when the track shape is non-rounded (flutter#164703)

Fixes [Discrete `Slider` and `RangeSlider` applies thumb padding when
using custom Slider
shapes](flutter#161805)

### Code Sample

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

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

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

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

  @OverRide
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        sliderTheme: const SliderThemeData(
          trackHeight: 32,
          trackShape: RectangularSliderTrackShape(),
          rangeTrackShape: RectangularRangeSliderTrackShape(),
          thumbColor: Colors.amber,
        ),
      ),
      home: Scaffold(
        body: Column(
          spacing: 20.0,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Slider(
              value: 100,
              max: 100,
              divisions: 100,
              onChanged: (double value) {},
            ),
            RangeSlider(
              values: const RangeValues(0, 100),
              max: 100,
              divisions: 100,
              onChanged: (RangeValues values) {},
            ),
          ],
        ),
      ),
    );
  }
}
```

</details>

### Before

<img width="929" alt="Screenshot 2025-03-06 at 13 33 17"
src="proxy.php?url=https://github.com/user-attachments/assets/a089674f-4931-4808-9663-1cd540bf7b11"
/>

### After

<img width="929" alt="Screenshot 2025-03-06 at 13 33 28"
src="proxy.php?url=https://github.com/user-attachments/assets/77fe5708-f2e4-4734-92c2-46e4d8338d0e"
/>

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
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
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)

…ht padding when the track shape is non-rounded (flutter/flutter#164703)