Date picker labels display unresolved translation keys in non-English locales

[jorgeltd]

Describe the bug

DSpace version: 2025.02.01.01
In non-English locales, the input labels for Year, Month, and Day within date picker form components concatenate the already-translated label string onto the translation key path instead of using the raw key slug. This results in the UI displaying raw, unresolved i18n translation keys (e.g., form.number-picker.label.Año instead of Año).

To Reproduce

Steps to reproduce the behavior:

1. Navigate to any submission form containing a date picker input (e.g., Publication).
2. Switch the application language to any language other than English (e.g., Spanish, French, German).
3. Inspect the Year, Month, and Day input labels in the date picker component.

Expected behavior

Render the translation for each date component correctly.