Remove hard-wired reference file from guider_cds step

[stscijgbot-jp]

Issue JP-3865 was created on JIRA by Tyler Pauly:

SDP nightly auto runs uncovered a CRDS fetch error for FGS ID data, described in CRDS-921. Once the rmap update in that ticket is completed, we can look into removing the "hard-wiring" of the readnoise and gain reference files still in the guider_cds code.