pmt gain, photoelectronsToAnalog, set to 4.24 by 20 to work around saturation in PbPb simulation; this assumes also a corresponding check of conditions
-- 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.
Merge pull request #2035 from iik1997/cas-mc-digi-step-scaledown20-in-sync-with-53X-rereco-mc-conditions

Scale down Castor photoelectron gain at digi step to avoid saturation in simulation of PbPb