Trigger should consider not all channels are in tpc

[JelleAalbers]

Right now the trigger triggers on trigger signals computed by considering all channels in all detectors. So if the threshold is 10 pulses, 8 tpc pulses plus some diagnostic pulses or later maybe acquisition monitor pulses could cause a trigger. That's a bit strange: let's make the trigger work only on TPC pulses by default, we can consider more complicated things later.