The work in fa509224f0 updated our initializer patterns to match modern Ember. This caused the initializer from the (deprecated) ember-export-application-global addon to change its behavior from exporting the ApplicationInstance to exporting the Application. This affects customizations which were using some long-deprecated APIs we had attached to the ApplicationInstance.
This commit removes the deprecated addon, restores the previous ApplicationInstance behavior which we've come to depend on, and adds a test for the expected behavior. It also bumps the `dropFrom` version to make it clear that we do not intend to remove these APIs during this release cycle.