Create separate Hudson job for classloader leak tests

The classloader leak tests can introduce instability into a testsuite run due to their need to try to force SoftReferences out of VM memory. When run without JVMTI available this involves deliberately overflowing memory, which is a) slow b) introduces instability.

So, we want to remove these tests from the main testsuite run. But we still want them executed, so create a separate Hudson job to run them.