REFACTOR: Continue to converge on what Ember CLI wants us to do (PR #10934)

  • The creation of a testing div is specific to Rails, so that is moved back out of setupTests();

  • We’ve removed the Discourse globals from the acceptance helpers in favor of setApplication/getApplication.

  • We pass the container to setupTests because there is no __container__ in later Ember versions.

  • App is now app because it’s not a constant or class, it’s an instance of an application.