This change was originally made in preparation for a BD-14
change that would enable database-backed organizations
across Open edX. Since then, we've figured out a way
of rolling out database-backed organizations without
mandating that organization slugs in new courses are
validated. So, this puts devstack back to where it was before,
with ORGANIZATIONS_APP==True for LMS on devstack and
ORGANIZATIONS_APP==False for Studio on devstack.

From a developer perspective, this means that course
runs can again be created in Studio with any org slug.

TNL-7425