RFR(S): 8152989: serviceability/tmtools/jstat/GcCauseTest02.java fails with OOME

[Per Liden]

Summary: This patch updates the tests in serviceability/tmtools/jstat/ 
to use a fixed (and relatively small) heap size. Without this these 
tests tend to run out of memory on machines with VM overcommit disabled. 
This has happened in nightly testing.

The patch also moves a misplaced @ignore tag and cleans out an unused 
method.

Testing: Without this patch I can easily get these tests to OOM on my 
local workstation by just disabling VM overcommit. They pass with this 
patch applied.

Bug: https://bugs.openjdk.java.net/browse/JDK-8152989
Webrev: http://cr.openjdk.java.net/~pliden/8152989/webrev.0/

cheers,
Per