Previously we only read the test class name from JUnit xml result. When the worker build fails prematurely, the JUnit xml result is not available. This PR fixes this issue by adding test class name to scenario list.
Previously, we collect all exceptions in the performance test execution then `assertEveryBuildSucceeds()`. This doesn't make any sense - we don't need to run the test any more if there's a failure. This PR fixes this issue by failing fast in performance iterations.
Also, we have 4 kinds of checks, which makes things complicated. This PR removes them and use `true/false` instead.