Fix executing Specs tests via JUnit Platform and Vintage engine Prior to this commit, the JUnitPlatformTestExecutionListener parsed the unique ID to determine the class and method name for TestIdentifiers without children but with a ClassSource. This occurs when a Spock test class uses `@Unroll` on all its test methods. However, other testing frameworks such as Specs2 don't provide a unique ID that is parseable which lead to the methodName being null which cause a failure during serialization. The effect was that tests hung because the build VM was waiting for the worker to finish the tests it started.
The Spock-specific workaround in our listener is now replaced with a more robust one that always uses the methodName provided by the JUnit Platform instead of parsing it.