Repository: flutter
Issue: When `validator`of `TextFormField` widget returns an `AppLozalizations.of(context).translationKey` value, error message does not refresh with locale change
Labels: framework,a: internationalization,has reproducible steps,found in release: 3.19,team-text-input,found in release: 3.21

### Steps to reproduce

1. Create a Form in your Flutter App using a `TextFormField()`.
2. Localize your Flutter app according to [the docs](https://docs.flutter.dev/ui/accessibility-and-internationalization/internationalization).
3. Build simple form validation according to [the docs](https://docs.flutter.dev/cookbook/forms/validation), by returning a localized string via the `validator` (e.g. `AppLocalizations.of(context).myTranslation`).
4. Test the app using `flutter run`, and provide invalid input and trigger validation.
5. This will show an according error message displayed in the current app locale.
6. Trigger a locale language switch in your app (we're currently doing this using a provider to whose value the `locale` property of the `MaterialApp` / `CupertinoApp` listens to).

### Expected results

The locale should be switched in the entire app, to the language to which the locale switch occurred. 

### Actual results

Every string present in the app via `AppLocalizations.of(context)...` changes, except for the strings returned via the `validator` property in the `TextFormField()` widget & displayed in the way mentioned above before the language switch. Only a new call to `formKey.currentState.validate()` will refresh the validation error messages according to the newly selected language.

This issue has also been mentioned [on so](https://stackoverflow.com/questions/52217090/internationalization-problem-when-i-switch-languages), still without a really viable solution.

### Code sample

<details open><summary>Code sample</summary>

```dart
you may consider https://stackoverflow.com/questions/52217090/internationalization-problem-when-i-switch-languages as an example.
```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

[Upload media here]

</details>


### Logs

<details open><summary>Logs</summary>

```console
[Paste your logs here]
```

</details>


### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.16.4, on macOS 14.2.1 23C71 darwin-arm64, locale de-CH)
    • Flutter version 3.16.4 on channel stable at /Users/inkognito/dev/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 2e9cb0aa71 (2 months ago), 2023-12-11 14:35:13 -0700
    • Engine revision 54a7145303
    • Dart version 3.2.3
    • DevTools version 2.28.4

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/inkognito/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b829.9-10027231)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.0.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15A507
    • CocoaPods version 1.14.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2022.3)
    • Android Studio at /Applications/Android Studio.app/Contents
    • 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 17.0.6+0-17.0.6b829.9-10027231)

[✓] IntelliJ IDEA Ultimate Edition (version 2023.3.3)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 77.3.1
    • Dart plugin version 233.13763.5

[✓] Connected device (3 available)
    • iPhone 15 Pro Max (mobile) • 1EF3E08B-D6C6-4D80-89B7-A97F5CDA6C61 • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-17-0 (simulator)
    • macOS (desktop)            • macos                                • darwin-arm64   • macOS 14.2.1 23C71
      darwin-arm64
    • Chrome (web)               • chrome                               • web-javascript • Google Chrome
      119.0.6045.159

[✓] Network resources
    • All expected network resources are available.

• No issues found!

```

</details>