[Validator] Completed Luxembourgish translations
minor #10744 [Validator] Completed Luxembourgish translations (mweimerskirch)

This PR was merged into the 2.4 branch.

Discussion
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[Validator] Completed Luxembourgish translations

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | n/a
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
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bc66e8f [Validator] Completed Luxembourgish translations