When simulating 8x8SiPM_w_CSI_optial_grease.gdml with GPURaytrace ~30% of hits missing wrt G4 CPU

[ggalgoczi]

When simulating 1 million photons with GPUPhotonSource we get ~240k hits with eic-opticks and G4 CPU too. (Input parameters explained in #210 .)

However when we use GPURaytrace ~30% of hits are missing from G4 CPU side.