-- Set back Castor photoelectron gain (photoelectronsToAnalog) to the value appropriate for pPb simulation as it initially was for 1st 53X releases.
-- Added three custom fragments with the Castor photoelectron gain values appropriate for all possible cases that is for pp, pPb, PbPb simulation.
-- Tested the fragments both at GEN-SIM (the same way as it was working for original SimWithCastor_cff) and DIGI steps (where photoelectronsToAnalog is in fact used).
-- Each fragment requires a matching set of conditions (CastorGains).
-- Hopefully now the solution should be universal within 53X.