Staging-88

What's Changed

• Add infrastructure for litterbox and hotgov sandboxes by @abroddrick in #2275
• Issue #2006: Display associated domains and requests on user change form - [backup] by @rachidatecs in #2255
• Update model diagram by @abroddrick in #2256
• HOTFIX: Add in check for school district by @therealslimhsiehdy in #2287
• Add Anna to fixtures by @zandercymatics in #2291

Full Changelog: staging-87-hotfix...staging-88