[tests] Outerloop improvements

## Use the main test runner for Outerloop

This would allow running the Outerloop tests to run in the same setup as the main tests, which would reduce the instances of tests working fine in Outerloop but still being flaky in the main test run. And it would remove the differences between the two runs.

- [ ] Use the main test runner but with the flag to run only quarantined tests
- [ ] Complain about zero test runs, and update the test projects accordingly