Event builder must handle large gaps in data

[JelleAalbers]

@molinario reports the event builder can throw an error such as:

File "/home/xedaq/pax/pax/trigger_plugins/HandleEdgeThings.py", line 21, in process
last_i = find_last_break(times=data.pulses['time'],
TypeError: 'NoneType' object is not subscriptable

indicating the eventbuilder expected some pulses where there are none. Probably it isn't yet equipped to deal with the very low rate of the muon veto data stream, where sometimes there are no pulses at all for several seconds.