Out transactional mirrors do not currently have a cleanup job. This means packages are kept forever, or at least until specific mirrors are removed.
This means we may run out of space.
Need to first verify this is actually needed in practice once and are implemented.
Snapshots that are older than 14 days are removed.
Snapshots that are newer than 13 days are kept.
Packages that are referenced only by old (14 days and older) snapshots are removed.
Packages that are referenced by new (13 days and newer) snapshots are kept.
At least 1 snapshot and its referenced packages are kept, even if it's older than 14 days.