desispec.workflow.redshifts healpix bookkeeping (harmless?)

[sbailey]

Launching healpix redshifts is done with commands like

SURVEY=main; PROGRAM=backup
desi_healpix_redshifts --survey $SURVEY --program $PROGRAM --bundle-healpix 10

This generates warnings like

WARNING:redshifts.py:235:create_desi_zproc_batch_script: Unrecognized group='healpix', using jobdesc='customztile'

This appears to be harmless and the jobs are running correctly, but create_desi_zproc_batch_script should be updated to recognize the 'healpix' option. The original purpose of 'customztile' was for cases like 1x_depth, 4x_depth, etc. where we couldn't predict what combinations our future selves might use, but healpix is a pre-known case.