Draft: Track truth label full pile-up truth
The InDetTrackTruthOriginTool used to assign the trackTruthOrigin assumes that tracks from pile-up do not have any truthParticle associated. While this is true in standard samples, for full pile-up truth samples, such as the one used for Run-4 studies, pile-up tracks have their truth record saved so this criterion cannot be used to identify them. (Note that even in standard sample, this criterion is not 100% reliable as some secondaries particles from the hard-scatter event are also skimmed for the truth record, so the tracks labelled as pile-up are at least a mixture of pile-up tracks and secondaries).
This MR introduces a more robust criterion to identify pile-up tracks in case full pile-up truth samples are used, checking whether the associated truth record is among the truthParticle associated to the hard-scatter event.