Chemistry backfill test cleanup should handle errors gracefully

[kbighorse]

Context

Identified during review of #558 (558-radionuclides-backfill branch).

Problem

The after_scenario cleanup for chemistry backfill data in environment.py (lines ~747–835) performs a long chain of FK-ordered deletes with no try/except. If any single delete fails (e.g., an unexpected FK dependency), the session.commit() never runs, all cleanup is lost, and orphan data causes cascading failures in subsequent test scenarios.

Fix

Wrap the cleanup block in try/except. On failure, log the scenario name and error with exc_info=True so developers can diagnose. Consider a fallback that deletes observations by nma_pk_chemistryresults IS NOT NULL as a safety net.

Files

• tests/features/environment.py (after_scenario chemistry backfill cleanup block)

[github-actions]

Linked Jira ticket created: BDMS-617