Remove redundant optical physics processes (fail to compile with geant4 11.0.0)

https://eicweb.phy.anl.gov/EIC/NPDet/-/tree/master/src/plugins/src

These EICScintillationPhysics etc processes are also upstream in DD4hep, and in DD4hep 1.19+1 they will work with geant4 11.0.0. We shouldn't keep them around here.