Cleaning up unused CRMI/SCRMI fields

Some of these really don't make any sense. Some of them
look useful but don't actually do anything. Not adding
the migration yet because I still need to figure out what's
going on with these migrations.
Adding migration for CRMI cleanup

South wanted a bunch more things to be in this migration. One of
them was apply_multiplier_to_room_cap, which I remember adding a year
ago and there's already a migration for it. Another one was something
about the SATPrepTeacherModuleInfo, which I remember running into
when I was trying to make the migration for apply_multiplier_to_room_cap
a year ago. I don't know why it's doing this, but the migration
I'm committing here ran fine, so it's probably fine...until the next time
someone tries to change the CRMI or SCRMI and gets confused.
Merge pull request #1504 from learning-unlimited/crmi-cleanup

CRMI cleanup