Re-activate test coverage for latest ember-data

[ef4]

We paused testing of newer ember data releases at 4.4 because there was breakage there for a while. But we need to work through turning it back on.

Specifically, there is new breakage that is failing in ember-cli's CI: https://github.com/ember-cli/ember-cli/actions/runs/3399363131/jobs/5653135682

Probably the compat adapters need to be updated again, because one ember-data package refactored to be nearly a v2 addon but didn't actually flip the switch to being a v2 addon (which would have opted it out of the complexity of these compatibility rules).

[ef4]

That actual problem here is not something we can easily work around in embroider, see emberjs/data#8296 (comment)

[runspired]

@ef4 even after fixing that there seems to be something up, but I'm having a hard time determining if it's data-related or embroider-related because we also get errors with bumping to ember-source 4.9 on our embroider scenario and with bumping babel deps to latest patch.