config/hsc/processCcd.py: update maxOffsetPix

The expansion of the bbox search radius for reference objects to
bbox + maxOffsetPix (added in DM-9750) caused a significant regression
in the astrometric matching.  It seems this is due to an issue with how
matchOptimisticB is handling large numbers of reference stars.  The
default in obs_subaru of maxOffsetPix = 750 resulted in a significant
number of CCDs failing in processCcd (identified in DM-11020).  Here we
set that default to maxOffsetPix = 250 which effectively results in the
same number of CCDs in the RC dataset passing single frame processing
and equivalent quality based on a comparison of QA plots for the pre-
regression and post-fix runs.

config/hsc/processCcd.py

@@ -26,7 +26,7 @@
 config.calibrate.astrometry.wcsFitter.numRejIter = 3
 config.calibrate.astrometry.wcsFitter.order = 3
 config.calibrate.astrometry.matcher.maxMatchDistArcSec = 2.0
-config.calibrate.astrometry.matcher.maxOffsetPix = 750
+config.calibrate.astrometry.matcher.maxOffsetPix = 250
 
 # Do not use NO_DATA pixels for fringe subtraction.
 config.isr.fringe.stats.badMaskPlanes = ['SAT', 'NO_DATA']