Fix RangeSlider renders track when track colors are transparent (#162386)

### Description 

Fixes [`Slider` with transparent track colors and custom `trackHeight`
cannot reach the extreme
ends](https://github.com/flutter/flutter/issues/161210) but for
`RangeSlider`.

### 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> {
  RangeValues _values = const RangeValues(0, 100);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Column(
            spacing: 20,
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              SliderTheme(
                data: const SliderThemeData(
                  trackHeight: 100,
                  activeTrackColor: Colors.transparent,
                  inactiveTrackColor: Colors.transparent,
                ),
                child: RangeSlider(
                  values: _values,
                  max: 100,
                  onChanged: (RangeValues values) {
                    setState(() {
                      _values = values;
                    });
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

```

</details>


### Before

<img width="755" alt="Screenshot 2025-02-12 at 15 56 21"
src="https://github.com/user-attachments/assets/e8c88bd8-3c87-46e2-9f29-b945128ae93a"
/>


### After

<img width="755" alt="Screenshot 2025-02-12 at 15 56 09"
src="https://github.com/user-attachments/assets/5f9244e8-4d51-40f3-a3fc-afdf9dff9b35"
/>


## 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.
- [x] 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].

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[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

packages/flutter/lib/src/material/slider_theme.dart

@@ -2199,10 +2199,17 @@ mixin BaseRangeSliderTrackShape {
         sliderTheme.rangeThumbShape!.getPreferredSize(isEnabled, isDiscrete).width;
     final double overlayWidth =
         sliderTheme.overlayShape!.getPreferredSize(isEnabled, isDiscrete).width;
-    final double trackHeight = sliderTheme.trackHeight!;
+    double trackHeight = sliderTheme.trackHeight!;
     assert(overlayWidth >= 0);
     assert(trackHeight >= 0);
 
+    // If the track colors are transparent, then override only the track height
+    // to maintain overall Slider width.
+    if (sliderTheme.activeTrackColor == Colors.transparent &&
+        sliderTheme.inactiveTrackColor == Colors.transparent) {
+      trackHeight = 0;
+    }
+
     final double trackLeft = offset.dx + math.max(overlayWidth / 2, thumbWidth / 2);
     final double trackTop = offset.dy + (parentBox.size.height - trackHeight) / 2;
     final double trackRight = trackLeft + parentBox.size.width - math.max(thumbWidth, overlayWidth);

packages/flutter/test/material/slider_theme_test.dart

@@ -3050,6 +3050,45 @@ void main() {
     },
   );
 
+  // Regression test for https://github.com/flutter/flutter/issues/161210
+  testWidgets(
+    'RangeSlider with transparent track colors and custom track height can reach extreme ends',
+    (WidgetTester tester) async {
+      const double sliderPadding = 24.0;
+      final ThemeData theme = ThemeData(
+        sliderTheme: const SliderThemeData(
+          trackHeight: 100,
+          activeTrackColor: Colors.transparent,
+          inactiveTrackColor: Colors.transparent,
+        ),
+      );
+
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: theme,
+          home: Material(
+            child: SizedBox(
+              width: 300,
+              child: RangeSlider(
+                values: const RangeValues(0, 1),
+                onChanged: (RangeValues values) {},
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final MaterialInkController material = Material.of(tester.element(find.byType(RangeSlider)));
+
+      expect(
+        material,
+        paints
+          ..circle(x: sliderPadding, y: 300.0, color: theme.colorScheme.primary)
+          ..circle(x: 800.0 - sliderPadding, y: 300.0, color: theme.colorScheme.primary),
+      );
+    },
+  );
+
   group('Material 2', () {
     // These tests are only relevant for Material 2. Once Material 2
     // support is deprecated and the APIs are removed, these tests