Ensure TempDir cleanup is executed when validation fails

[scordio]

Overview

See #3901 (comment).

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Definition of Done

• There are no TODOs left in the code
• Method preconditions are checked and documented in the method's Javadoc
• Coding conventions (e.g. for logging) have been followed
• Change is covered by automated tests including corner cases, errors, and exception handling
• Public API has Javadoc and @API annotations
• Change is documented in the User Guide and Release Notes

[scordio]

Change is documented in the User Guide and Release Notes

I didn't add any release note about this change but let me know if we should have one.

[marcphilipp]

@scordio Thanks! 👍