Wrap Persistence and DelegateBelongsTo into AS.on_load

Help us avoid touching the db when loading the environment
Refactor DelegateBelongsTo to not touch db on startup

Plus remove AS on_load block on core engine

It was not working as expected anyway we'd need to execute that hook
later in the application and I have no idea where we would do that,
tried a bunch of places and none had the result expected