PrFTHitsChecker - errors w.r.t. missing mat objects in dd4hep builds

With !3048 (merged) a number of previously hidden errors in PrFTHitsChecker in the dd4hep builds are made apparent.

PrFTHitsChecker                       ERROR No mat is found for (1629.59, 0, 9402.9)
PrFTHitsChecker                       ERROR No mat is found for (1636.72, 0, 9402.9)
PrFTHitsChecker                       ERROR No mat is found for (1640.22, 0, 9402.9)
PrFTHitsChecker                       ERROR No mat is found for (1685.51, 0, 9402.9)

These need to be investigated.

FYI @lohenry @valukash @decianm