fix(files_sharing): Add correct context to translation

[susnux]

• Resolves https://github.com/nextcloud/server/issues/48733

This string is extracted in the files_sharing app so it needs to be accessed there and not on files.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• [x] Tests (unit, integration, api and/or acceptance) are included
• [ ] Screenshots before/after for front-end changes
• [x] Documentation (manuals or wiki) has been updated or is not required
• [x] Backports requested where applicable (ex: critical bugfixes)