[junitlauncher] - Switch back to issuing a separate LauncherDiscoveryRequest for each of the test class that are selected by the <testclasses> usage In 1.10.5 version (the latest released) of Ant, we used to launch multiple LauncherDiscoveryRequest (a JUnit 5 construct), one each for a test class, that belonged to the <testclasses> usage. Commit 3f806148c3f3542b8526d5f91f10d6189bf0607d changed it to launch one single LauncherDiscoveryRequest (and including all those test classes in that request) because it seemed more logical to do so. However, recent tests/experimentation of the master branch has shown that it introduces complexities when the "legacy-xml" listener (the one which supports generating test results in xml format that junitreport understands) is used. These complexities include - expecting each test class to have a separate report file, but isn't limited to that. Solving these issues isn't easy and probably not worth it, given that the only reason we started using a single LauncherDiscoveryRequest is because it just seemed logical and there is no other strong reason to do so. This commit switches back to the behaviour that's been there in 1.10.5 version, to issue multiple separate LauncherDiscoveryRequest(s) one each for the test class that's selected through the use of <testclasses>.