Repository: flutter
Issue: DropdownButtonFormField arrow icon is misaligned vertically
Labels: framework,f: material design,a: fidelity,has reproducible steps,P2,team-design,triaged-design,found in release: 3.24,found in release: 3.27

### Steps to reproduce

1. Run sample
2. Observe dropdown icon is aligned to where the content would be instead of the field as a whole

### Expected results

The dropdown icon should be vertically centered within the form field.

### Actual results

The dropdown icon is centered vertically relative to the selected content.

### Code sample

<details open><summary>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: Scaffold(
        body: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Center(
              child: SizedBox(
                width: 200,
                child: DropdownButtonFormField<String>(
                  onChanged: (_) {},
                  decoration: InputDecoration(
                    labelText: 'Label text',
                  ),
                  items: [
                    DropdownMenuItem(
                      value: 'selected',
                      child: Text('Selected item'),
                    ),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

Flutter:
![image](https://github.com/user-attachments/assets/3b967d4c-f41f-4188-88dd-a3f1ba0c5038)

M3 Design:
![Material 3 dropdown phases design](https://github.com/user-attachments/assets/f73b4e9d-71dc-4d96-af12-1446a47a442b)


</details>


### Logs

N/A

### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[!] Flutter (Channel [user-branch], 3.27.0-1.0.pre.87, on Microsoft Windows [Version 10.0.22631.4317], locale en-US)
    ! Flutter version 3.27.0-1.0.pre.87 on channel [user-branch] at C:\Users\bscho\.puro\envs\master\flutter
      Currently on an unknown channel. Run `flutter channel` to switch to an official channel.
      If that doesn't fix the issue, reinstall Flutter by following instructions at https://flutter.dev/setup.
    ! Warning: `flutter` on your path resolves to C:\Users\bscho\.puro\envs\stable\flutter\bin\flutter, which is not inside your current Flutter SDK checkout at C:\Users\bscho\.puro\envs\master\flutter. Consider adding       
      C:\Users\bscho\.puro\envs\master\flutter\bin to the front of your path.
    ! Warning: `dart` on your path resolves to C:\Users\bscho\.puro\envs\stable\flutter\bin\dart, which is not inside your current Flutter SDK checkout at C:\Users\bscho\.puro\envs\master\flutter. Consider adding
      C:\Users\bscho\.puro\envs\master\flutter\bin to the front of your path.
    ! Upstream repository unknown source is not a standard remote.
      Set environment variable "FLUTTER_GIT_URL" to unknown source to dismiss this error.
    • Framework revision 9bb056822e (62 minutes ago), 2024-10-16 22:52:18 -0400
    • Engine revision e2188ee9ab
    • Dart version 3.6.0 (build 3.6.0-334.2.beta)
    • DevTools version 2.40.1
    • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and upgrades.

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at C:\Users\bscho\AppData\Local\Android\sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: C:\Program Files\Android\Android Studio\jbr\bin\java
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-10027231)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • CHROME_EXECUTABLE = C:\Program Files\BraveSoftware\Brave-Browser\Application\brave.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.11.4)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.11.35312.102
    • Windows 10 SDK version 10.0.22621.0

[√] Android Studio (version 2023.2)
    • Android Studio at C:\Program Files\Android\Android Studio1
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.9+0--11185874)

[√] Android Studio (version 2022.3)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = C:\Program Files\Android\Android Studio
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-10027231)

[√] VS Code (version 1.94.2)
    • VS Code at C:\Users\bscho\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.98.0

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.22631.4317]
    • Chrome (web)      • chrome  • web-javascript • unknown
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 129.0.2792.89

[√] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.
```

</details>