Build preriodically with bootstrap macro enabled.

The packaging guidelines provides a way to bootstrap packages [[1]]. It would make sense to periodically enable this macro in buildroot to break the loops requiring bootstrapping. That would help with failures such as [[2]].

[1]: https://docs.fedoraproject.org/en-US/packaging-guidelines/#bootstrapping
[2]: https://koji.fedoraproject.org/koji/taskinfo?taskID=53065706