[4.0] Fix language constant

[Quy]

Pull Request for Issue #25959.

Summary of Changes

Fix language constant.

Testing Instructions

1. Log in into Joomla 4.x Alpha 12dev administration
2. Click on Add Module to the Dashboard in any admin dashboard

Actual result

String not translated.

[brianteeman]

I have tested this item ✅ successfully on 613c011

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[richard67]

I have tested this item ✅ successfully on 613c011

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[Quy]

RTC

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[jeckodevelopment]

Thanks @Quy

[infograf768]

Tks