Fix: Update test assertions and simplify test cases (#9400)
### What problem does this PR solve?
- Fix error message assertion in test_update_chunk.py to match new
ownership validation
- Simplify dataset listing test cases by removing lambda assertions for
sorting
- Fix actions:
https://github.com/infiniflow/ragflow/actions/runs/16885465524/job/47831942553
### Type of change
- [x] Fix test cases