RFR: 8201609 - Split test/jdk/:tier2 to enable better parallel execution

[Christian Tornqvist]

Please review this small change that splits the tier2 test group into three smaller test groups that can be executed in parallel.

Webrev: http://cr.openjdk.java.net/~ctornqvi/webrev/8201609/webrev.00/ <http://cr.openjdk.java.net/~ctornqvi/webrev/8201609/webrev.00/>
Bug: https://bugs.openjdk.java.net/browse/JDK-8201609 <https://bugs.openjdk.java.net/browse/JDK-8201609>

Thanks,
Christian