Plan:
- [x] Package swh.scheduler v0.17.0
- [x] Upgrade python3-swh.scheduler on scheduler0.staging
- [x] Migrate db version from 28 to 30 (impacted tables: origin_visit_stats, scheduler_metrics)
- [x] Restart gunicorn-swh-scheduler and other scheduler services
- [ ] Ensure the journal client is still ok