minor symfony#61251 [Validator] Add Japanese translation for Twig template validator (takashiraki)

This PR was squashed before being merged into the 6.4 branch.

Discussion
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[Validator] Add Japanese translation for Twig template validator

Fixes symfony#60465

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#60465
| License       | MIT

## Summary

This PR adds the missing Japanese translation for the Twig template validator constraint as requested in issue symfony#60465.

## Files Modified

- `src/Symfony/Component/Validator/Resources/translations/validators.ja.xlf`

## Translation Details

The translation maintains consistency with existing Japanese validator messages by:
- Keeping technical terms like "Twig" in the original form
- Following the natural Japanese expression patterns

## Testing

- [x] XML syntax validation passed
- [x] All existing tests continue to pass
- [x] Translation follows the established style guide

Commits
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1f4b356 [Validator] Add Japanese translation for Twig template validator

Author: nicolas-grekas