Fix incorrect translation key for parameter_not_allowed.detail

[pozzer]

Closes #1468.

All Submissions:

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• My submission passes all tests. (I ran the full test suite locally to avoid unnecessary failures.)
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• I've added/updated tests for this change.

Bug fixes and Changes to Core Features:

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• I've provided test(s) that fail without the change.

Test Plan:

The issue occurs because the translation key being used in the code is incorrect.
The code currently looks for parameters_not_allowed.detail (plural), but the correct key in the translation files is parameter_not_allowed.detail (singular).

• Added a test to verify that the correct key (parameter_not_allowed.detail) is used.
• Without the fix, the test fails because the translation isn't found, falling back to the default English message.
• With the fix, the test correctly retrieves the translation.

Reviewer Checklist:

• Maintains compliance with JSON:API
• Adequate test coverage exists to prevent regressions