RFC-645, obs_sdss and lsst_dm_stack_demo should be removed from the default stack build. obs_sdss appears in both lsst_apps and lsst_obs. lsst_dm_stack_demo is a little less clear and needs some investigation to figure out where to remove it.
This should be done after
DM-22577, which will ensure that there's some basic verification of functionality in a stack installation.