Make legacy configuration for the ExtraParticles G4Extension more robust Improved configuration to avoid causing problems in the case of running with other G4Extensions which add new particles. Should fix ATLASSIM-5960
Also, in the CA-based configuration move specialConfig preIncludes after command-line preIncludes in simulation jobs.
This is necessary to maintain agreement between old and new-style configuration when
G4GammaGeneralProcess is activated (as it is by default in MC21).