Problem: PREMIS XML validation fails after /tmp cleanup

[jraddaoui]

Describe the bug

The preprocessing-sfa worker’s custom XML validation activity writes an embedded PREMIS XSD to /tmp and caches the generated file path in an activity struct field. If /tmp is cleaned, the cached path remains set and the activity does not recreate the file, so validation fails until the worker restarts.

To Reproduce

1. Run preprocessing-sfa worker and execute a workflow that reaches the PREMIS XML validation step.
2. Confirm the activity generates an XSD file in /tmp (e.g. premis-v3-*) and validation succeeds.
3. Clean /tmp (or delete the generated premis-v3-* file).
4. Run the validation step again without restarting the preprocessing worker.
5. Observe validation failing because the activity continues using the cached /tmp path but does not recreate the missing file.

Expected behavior

• The preprocessing-sfa worker should not fail PREMIS XML validation due to /tmp cleanup.
• If the XSD file used for validation is missing, the activity should recover automatically without requiring a worker restart.
• Avoid relying on a non configurable /tmp location for schema validation.

Additional context

This issue is related to a temporal-activities feature request to extend the existing xmlvalidate activity so it can support both filesystem XSD paths and embedded XSD content. Once that is available, preprocessing-sfa could switch to the shared activity and drop the custom temp file implementation (see temporal-activities issue).