Fixes#71
## Why
`FindOrphanedBlobs` returned any blob not currently referenced. Because CAS dedups (the blob row can exist before its artifact/local_files row is written), a concurrent upload reusing an existing hash could have its S3 object deleted mid-flight by the GC.
## Changes
- `FindOrphanedBlobs` now takes a `minAge` and only returns blobs with `created_at < now()-minAge`.
- The collector passes a 1h `blobGracePeriod`.
## Validation
- `go test ./internal/gc/...` and `make e2e` pass.
---------
Co-authored-by: BenVincent <benvin@main.unkin.net>
Reviewed-on: #86
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
unkinben
e7c9387bcc