PhotoCal should not use MatchOptimisticBTask

PhotoCalTask currently inherits from lsst.meas.algorithms.RefMatchTask, which defaults to using the MatchOptimisticBTask for matching. The MatchOptimisticBTask is a full-featured matcher allowing for offsets and rotations, but by the time photometric calibration is required we are expected to have done all astrometric calibration and the use of a full-featured matcher is inviting trouble and requires unnecessary duplication of configuration changes (i.e., any configuration changes need to be mirrored from calibrate.astrometry.matcher to calibrate.photoCal.matcher).

I suggest changing the PhotoCalTask to use the DirectMatchTask, in which case the inheritance from RefMatchTask could be removed, greatly simplifying the design.