Figure out why some tests need application-template-wrapper enabled to pass

As part of my work to [upgrade ember-cli-fastboot using ember-cli-update](https://github.com/ember-fastboot/ember-cli-fastboot/pull/834) I noticed that some tests failed because they needed the application-template-wrapper to be enabled in optitonal-features.

I didn't really have the time to investigate why, and I didn't want to block the other PR any more than it already was 🙈 so this issue is to keep track that it needs to be looked into.

To test this, just undo the work in [this commit](https://github.com/ember-fastboot/ember-cli-fastboot/pull/834/commits/b7c393470773119b1fd21a7e538a8f560c62530c) and see why some tests fail 🤷 I have a feeling it could just be a selector depending on the wrapper div existing 🤔