add a test for getAllTestResults

[SophieDePaula]

No description provided.

[amitzur]

While the functionality that is tested here is new and not covered by any other test, the goal was to add coverage to delete test results.

So let's keep this test as is, but also delete the test results and verify that they were deleted. (and update the name of the test to reflect it).

Additional notes:

1. Any reason to do this only for vg? Please add a classic variant as well.
2. Did you need to save a new baseline for this test? If so, I think it's unnecessary, as this test is not checking the visual output. Please pass false to eyes.close to avoid the need for a baseline here.