[material_ui] Enable localized time_picker_test cases

[elliette]

Follow up to #12061, #12119

Port over the remaining time_picker_test cases from flutter/flutter#184279 that were initially excluded in #12061 due to lack of localization support in material_ui.

Work towards flutter/flutter#182636 and flutter/flutter#188395

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[gemini-code-assist]

Code Review

This pull request adds regression and localization tests for the TimePicker widget, covering 24-hour Farsi formatting, centered separators in non-English locales, and spacing in locales using the 'a h:mm' pattern. It also updates the mediaQueryBoilerplate helper to support custom locales. Feedback recommends explicitly passing alwaysUse24HourFormat: true in the Farsi test to ensure robustness, and parameterizing the theme and golden file names in the separator alignment test to prevent test overwrites across different material types.

[gemini-code-assist]

The test is named 'Material3 - formats 24-hour numbers correctly in Farsi', but alwaysUse24HourFormat: true is not explicitly passed to mediaQueryBoilerplate. To ensure the test is robust and explicitly tests the 24-hour format regardless of any default locale settings, please pass alwaysUse24HourFormat: true.

    await mediaQueryBoilerplate(
      tester,
      alwaysUse24HourFormat: true,
      locale: const Locale('fa', 'IR'),
      materialType: MaterialType.material3,
    );

[elliette]

Valid suggestion, though I'm guessing the Farsi locale always uses 24-hours anyways? The test case as it is matches the original in flutter/flutter: https://github.com/flutter/flutter/blob/1abf8f42d372614c02ad78d1a00f3720f05af74c/packages/flutter/test/material/time_picker_test.dart#L239

[gemini-code-assist]

This test is defined inside the for (final MaterialType materialType in MaterialType.values) loop, meaning it runs twice (once for Material 2 and once for Material 3). However, it currently has two issues:

1. It pumps a MaterialApp without specifying a theme, so it always uses the default theme (Material 3) in both runs, leaving Material 2 untested.
2. Both runs use the exact same golden file name ('time_picker.dialog.separator.alignment.non_english_locale.png'), which causes them to overwrite each other and can lead to flaky or incorrect test results.

To fix this, configure the MaterialApp's theme using materialType and parameterize the golden file name using ${materialType.name}.

      testWidgets(
        'TimePicker dialog displays centered separator between hour and minute inputs for non-english locale',
        (WidgetTester tester) async {
          tester.view.physicalSize = const Size(400, 800);
          tester.view.devicePixelRatio = 1.0;
          addTearDown(tester.view.reset);

          await tester.pumpWidget(
            MaterialApp(
              theme: ThemeData(useMaterial3: materialType == MaterialType.material3),
              localizationsDelegates: GlobalMaterialLocalizations.delegates,
              supportedLocales: const <Locale>[Locale('en'), Locale('es')],
              locale: const Locale('es'),
              home: const Material(
                child: TimePickerDialog(
                  initialTime: TimeOfDay(hour: 12, minute: 0),
                  initialEntryMode: TimePickerEntryMode.input,
                ),
              ),
            ),
          );
          await tester.pumpAndSettle();

          await expectLater(
            find.byType(Dialog),
            matchesGoldenFile('${materialType.name}_time_picker.dialog.separator.alignment.non_english_locale.png'),
          );
        },
      );

[elliette]

Again, seems like a valid suggestion but this matches the original test case: https://github.com/flutter/flutter/blob/1abf8f42d372614c02ad78d1a00f3720f05af74c/packages/flutter/test/material/time_picker_test.dart#L1538

[justinmc]

LGTM 👍