RFR (XS): 8193067: gc/g1/TestVerifyGCType.java still unstable

[Thomas Schatzl]

Hi all,

  can I have reviews for this small change to the TestVerifyGCType test
to make it stable? The problem has been that due to different number of
threads used, different amount of heap waste has been "produced", only
randomly triggering the expected mixed gcs.

By fixing the number of threads used and decreasing G1HeapWastePercent
the mixed gcs can be forced reproducably.

CR:
https://bugs.openjdk.java.net/browse/JDK-8193067

Webrev:
http://cr.openjdk.java.net/~tschatzl/8193067/webrev/

Testing:
failing test passing multiple times in CI

Thanks,
  Thomas