## Description
Add a regression test component to the retention test. This ensures that setting all values to 0 causes it to keep MaxInt latest snapshots.
## Type of change
<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor
## Issue(s)
* closes#906
pending merge of
* kopia/kopia#2454
## Test Plan
<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E