Test swh-alter delete/restore on production-like data

swh/devel/swh-alter> allows to remove data from the archive. Before doing so, it creates a recovery bundle that can be used to restore what was removed. One of its use will be to replay a removal operation in case a relevant addition to the archive has been made while the removal process whan on-going.

Ideally, the archive should be the same after a delete+restore than it was before. It would be good to be able to test the process on random set of origins from production as what we found in-the-wild has been sometimes very surprising. This would help not having to fight a bug at a later time, when we really need to restore something.

This probably could wait until swh/devel/swh-alter#2 (closed), swh/devel/swh-alter#3 (closed), swh/devel/swh-alter#4 (closed), swh/devel/swh-alter#5 (closed) are done.