Disable "other" cryostat keys for visible/nir cryostats

We have a handful of FITS cards which are generated for both NIR and visible cryostats which make no sense for one of them (SAM power, cooler2, visTemps-vs-nirTemps), and now have a couple which have the same name but different sources (a couple of the temperatures).

On actor startup, immediately after the models are loaded, prune the inappropriate ones. I looked into subclassing from a common KeyDictionary, etc., but all schemes I could come up with were worse, I think.