MCR-3580 Uploading files with some special characters fails before filename can be validated

[toKrause]

Link to jira.

Pull Request Checklist (Author)

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Ticket & Documentation

• The issue in the ticket is clearly described and the solution is documented.
• Design decisions (if any) are explained.
• The ticket references the correct source and target branches.
• The fixed-version is correctly set in the ticket and matches the PR's target branch (2025.06.x).

Feature & Improvement Specific Checks

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• Does this change affect existing applications, data, or configurations?
  • Yes: Is a migration required? If yes, describe it.
  • Breaking change is marked in the commit message.

Bugfix-Specific Checks

• Affected version is listed in the ticket.
• Minimal code changes were made (no refactoring).
• This PR truly fixes only the reported bug.
• No breaking changes are introduced.
• A relevant test was added (if feasible).

Testing

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• The feature behaves as described in the ticket.
• Were existing tests modified?
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MCR Conventions & Metadata

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Multi-Repo Considerations

• Is an equivalent PR in MIR required?
  • If yes, is it already created?