Fix: Increase timeouts for document parsing and model checks (#8996)
### What problem does this PR solve?
- Extended embedding model timeout from 3 to 10 seconds in api_utils.py
- Added more time for large file batches and concurrent parsing
operations to prevent test flakiness
- Import from #8940
- https://github.com/infiniflow/ragflow/actions/runs/16422052652
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)