Improve testdouble.js usage

Running the tests locally I saw several admonishements similar to this one:

```
Warning: testdouble.js - td.verify - test double was both stubbed and verified with arguments ({
packages: ["ember-cli-qunit@1.2.0"],
save: false,
"save-dev": true,
"save-exact": false,
packageManager: undefined
}), which is redundant and probably unnecessary. (see: https://github.com/testdouble/testdouble.js/blob/main/docs/B-frequently-asked-questions.md#why-shouldnt-i-call-both-tdwhen-and-tdverify-for-a-single-interaction-with-a-test-double )
```

We should clean that up so the test output is the cleanest possible.