JUnit reports should be captured on test failures

The test reports were not being generated correctly when a test failure occurred (they would be blank). This change uses files as artifacts for the test output and test exit code. This way the job can proceed after a test failure, and the output and exit code and be used later to generate the report and pass/fail the job.

You can see here that even though the race job failed, the test report is still populated with the offending test: