In JDK-8213184, a rushed revert was pushed to stop breaking CI builds. A long-term solution is needed, where test-prebuilt can be restored to jib-profiles.js. This will require the run-test-prebuilt top-level make target in Help.gmk to be updated as well. Also, Help.gmk should really change name to signify that it's not just help targets, but all global targets (some definitely more significant!)