Improve HellThreadPolicy
Make an option (probably something like config :pleroma, :mrf_hellthread, reject: false
) to instead of rejecting the activity, check if activity is public and if it is, remove everything, but https://www.w3.org/ns/activitystreams#Public
and followers collection from to
and cc
and make it unlisted. Should probably also list the threshold in nodeinfo, but that's to be discussed