batches: Rethink filters on batch change page

Created by: eseliger

We recently defaulted to "All" as the standard, because we felt that Draft BCs were hidden too much. While I agree, I think this causes another problem, especially on the global list, where the list might be extremely long by default because it includes all those closed ones from the past. Maybe we should default to draft + open, instead of "All", like GitHub does for PRs and issues?