[TESTBUG] java/lang/instrument/DaemonThread/TestDaemonThread.java fails when run by jprt

One of the changes done for JDK-8161225 was to have it properly check the exit value of subprocesses it creates. Previously it just made sure there was no ASSERT message in the output. The extra check is catching failures (presumably pre-existing) that only seem to turn up with run under jprt, and for that matter only when run with a batch of tests (using jdk_instrument test group or jdk/test/java/lang/instrument path). It does not fail standalone under jprt, and it does not fail when run under RBT, even as part of a batch.

The failure seems to be classpath related, and is causing TestDaemonThreadLauncher not to be able to find TestDaemonThread when it launches it as a subprocess.