Jan Snasel

> * [ ] Come to a conclusion about SET_NULL vs PROTECT on `Controller.external_integration` ([Initial work on Controller Models #5325 (comment)](https://github.com/nautobot/nautobot/pull/5325#discussion_r1526772273)) and `Controller.deployed_controller`/`Controller.deployed_controller_group` ([Initial work on Controller Models #5325 (comment)](https://github.com/nautobot/nautobot/pull/5325#discussion_r1526772664))...

Both fields can be null, so keeping `SET_NULL`, no change is necessary.

As we are still on beta, I just updated the migration.