This removes our query to FAS and fixes#304.
It is more flexible too, where we can now configure production to only
allow in members of the `modularity-wg` group, and then later open it up
to all packagers after F26 is out (as was agreed with FESCo).
In the process of working on this, I discovered that #305 is not
necessary. We don't need our own scope; we can just use the `groups`
scope as done here.
