DM-35035: Remove gen2 curated calibration code

[timj]

The core reader code has been moved to lsst/obs_base#424

[erykoff]

Looks good. Sorry I missed that gen2 test previously!

[erykoff]

One more question I just realized: this code used to be a public interface in pipe_tasks but is now private in obs_base. Is there a need to do a deprecated forwarding here?

[timj]

read_all was public because obs_base needed to call it. The real public interface was the gen2 ingestCuratedCalibs.py. I was pondering whether read_all should be public in obs_base to allow Instrument subclasses to call it directly but I decided not to unless we need it because the actual curated calibrations interface in Instrument is much better. If we want this code to hang around for a deprecation cycle I should bring it back rather than calling obs_base because the interface has changed in obs_base. Given there's a tiny chance that someone has used read_all outside of a butler context (Which is tiny since they also need the corresponding obs_*_data package layout) then I'll bring it back and add a deprecation.

[timj]

I've added the deprecation message.