Introduce occupancy cuts for 2D space point formation

In data, we observed a huge number of RPC space points, even more than Mdt space points.

Initial checks on showed that there are on average 20 rpc hits per gasGap. If we don't cluster the measurements, other means have to be found to reduce the number of space points. Proposal to build 2D space points only if the chamber occupancy is low enough. Introduce technology dependent thresholds on the channel occupancy.