allow more than one instance of the tests to run at a time

[diosmosis]

Currently, the tests require that an Apps Script project be setup beforehand, and this project deployed to it. This is fine for local development, but within CI, this means only one build can be running at a time.

To fix this:

• before a test run, create a new test Apps Script project (also delete any existing test Apps Script projects that were not deleted)
• delete the test project when done