Finish porting tests from QUnit to jest

[ef4]

We have some tests in QUnit and some in jest. When the whole suite runs, jest invokes QUnit. It would be better to factor out the remaining use of QUnit and have one thing.

cc @Turbo87

[stefanpenner]

@ef4 how are you enjoying jest?

[ef4]

It's fine. Mostly it was a good choice here because it replaced a perl & bash based parallel runner for our various test suites. I don't think it's necessarily better than QUnit at the level of authoring individual tests.

@stefanpenner: related to test ergonomics, I think I'm still seeing babel/broccoli-babel-transpiler#169 in the embroider test suite. It manifests as a timeout when the jest-invoked QUnit process fails to exit, even though QUnit got to the end of its suite.

[stefanpenner]

@ef4 oh, I forgot about that. Does it reproduce consistently for you?

I'll add this to my todo list, please feel free to remind me if it isn't addressed soon.