Clean up code referring to (unused) PixelModule.h
In LHCb there was a PixelModule.h, that is also duplicated in Rec as PrPixelModule.h. This class seems to be a relic from a previous iteration of the velo tracking and is no longer actually used. This MR removes the references to this file.
Tagging @ahennequ for possible review.
Goes with LHCb!4382 (merged)
Edited by Laurent Dufour