text: Title: `test_import.py` module is large and can be broken up into smaller modules
  Body: `tests/admin_integration/test_import.py` is now over 1k lines and should be broken up into smaller test modules.
  
  Also
  
  - look at adding helpers to remove code duplication
  - Refer to URLs using constants in `admin_integration/mixins.py` rather than magic strings
  