Add pixel dEdx output to IDPVM.
Adds the pixel dE/dx to the histogram and ntuple output of IDPVM. It is an existing "track summary" property, so it seems appropriate to add it to IDPVM with the other track summary variables.
The histograms are added under SquirrelPlots/Tracks/Selected/HitsOnTracks/pixeldEdx
(InDetPerfPlot_Hits
class) as that's where all "track summary variables are added. Also it's calculated from the hits.
Also remove unused --doLowPtTracks
option to runIDPVM
that was mistakenly left in !51575 (merged).
Tagging @goblirsc for comments from IDPVM side.