What's the problem this feature will solve?

Our builds table is huge, we shouldn't keep these objects forever.

Describe the solution you'd like

Delete builds after some months (3, 9, 12?), but also keep at least the last 5/10 builds from each version, so projects still have some historical data about the last time they were built. We should also start deleting build artifacts from storage as well.

We could also go back to delete builds when a version is deleted (cascade delete instead of set to null).

Additional context

There was a meeting about this, I wasn't there, but looks like people were okay with deleting build objects.