Update jprt runthese test suite to jck-8

The runthese test suite, while having been a good friend almost more than a decade, is showing some age and should be updated. Some of the tests are taking unnecessarily long to run and updating the tests to be based on jck-8 will address this.

It would also be beneficial to split up the long running linux_i586-fastdebug-Xcomp to take advantage of the parallelism in jprt - it has been found to often be one of the last running tests and is therefore often a bottleneck from a job time perspective.