Clean up - squash migrations, delete fix management commands

We should create a branch for legacy systems that we migrate up to, then switch back to master

Need a way to force all deployments into branch. Could potentially leave a throw value error in master, say to switch branches going forward then fix that in the branch. Though that would disappear when we cleaned out migrations in master. Perhaps a manual migration?

Doing this we can squash migrations etc - and delete a lot of old management commands.

No files, tests, or entry points are named. Begin by identifying the migration history and management commands affected, then define the legacy branch and deployment workflow before verifying that migrations can be squashed without breaking upgrades.

Written by the indexing model from the issue text.