Add back logic to run tests with `CreateDefault()` in addition to `CreateDefault2()`

[andyleejordan]

In #1547 we're fixing the production code to strictly use CreateDefault2() as it was always intended to use. There was somewhat defunct code to run the tests with CreateDefault() instead. We need to add a separate TestCreateDefault build task and associated logic to specifically test CreateDefault() as a separate test suite, since it helps assert that "things work with auto-discovered commands."