Fix the type error by removing translation for system error messages

Problem/Motivation

When the image fails to process or load, a type error appears:
TypeError: Symfony\Component\HttpFoundation\Response::__construct(): Argument #1 ($content) must be of type ?string, Drupal\Core\StringTranslation\TranslatableMarkup given, called in /app/docroot/modules/contrib/drimage_improved/src/DrimageManager.php on line 429 in Symfony\Component\HttpFoundation\Response->__construct() (line 224 of /app/vendor/symfony/http-foundation/Response.php).

Proposed resolution

Ensure the error message is a string by casting it to a string type.

Remaining tasks

• ✅ File an issue
• ✅ Addition/Change/Update/Fix
• ✅ Testing to ensure no regression
• ➖ Automated unit testing coverage
• ➖ Automated functional testing coverage
• ➖ UX/UI designer responsibilities
• ➖ Readability
• ➖ Accessibility
• ➖ Performance
• ➖ Security
• ➖ Documentation
• ✅ Code review by maintainers
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Release notes snippet
• ✅ Release drimage_improved-1.0.6, drimage_improved-1.0.7

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3469425 by qusai taha: Fixed the type error by removing translation for system error messages