Remove TruthIncident which was causing Fatras to crash
An ISFTruthIncident was being registered in the McMaterialEffectsUpdator
when a neutral particle simply deposited energy and was otherwise unchanged.
The particle continued to be propagated, which then lead to the TruthSvc
trying to add an end vertex for a particle which already had an end vertex.
Should fix ATLASSIM-4120.
Edited by John Derek Chapman