Determine whether to use UTR deltas by looking at exposureType

The H4 isrTask currently controls whether to make CR and ASIC glitch corrections using UTR deltas by trying to figure out whether there are "enough" illuminated reads to correct across. This is finicky, as is tracking the book-keeping downstream. In nearly all cases it would be simpler and safer to simply use the ramp's DATA-TYP / .exposureType: we should only correct object and dark ramps using UTR, and arc/flat exposures using CDS and deferring CR correction to later medians of multiple exposures.

There are edge cases. Oh, truncated object ramps or recovered failed ramps. If they are short enough not to be safely correctable we might not care about them?