fixes [Secondary `TabBar` indicator height token is missing ](https://github.com/flutter/flutter/issues/124965)

### 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 MaterialApp(
      debugShowCheckedModeBanner: false,
      home: DefaultTabController(
        length: 2,
        child: Scaffold(
          appBar: AppBar(
            title: const Text('Sample'),
            bottom: const TabBar.secondary(
              tabs: <Widget>[
                Tab(icon: Icon(Icons.directions_car)),
                Tab(icon: Icon(Icons.directions_transit)),
              ],
            ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: () {},
            child: const Icon(Icons.add),
          ),
        ),
      ),
    );
  }
}
```

</details>