Update the segmentation.txt  https://github.com/lsst-ts/phosim_syseng4/blob/aos/data/lsst/segmentation.txt  gain and read noise values to make them consistent with those in lsstCamMapper ( eg. https://github.com/lsst/obs_lsst/blob/master/policy/lsstCam/R00.yaml ). 

Currently, the values in `segmentation.txt` are consistent with PhosimMapper, but DM-26836 creates a need to move to LsstCamMapper. Thus the calibration files (made with `makeGainImages.py` https://github.com/lsst-dm/phosim_utils/blob/master/bin.src/makeGainImages.py need to use geometry and gain values consistent with LsstCam.