RFR:8150067:Quarantine serviceability/tmtools/jstat/GcCapacityTest.java test

[Alexander Kulyakhtin]

Hi,

Could you, please, review this trivial test-only change (quarantining the test):

CR: https://bugs.openjdk.java.net/browse/JDK-8150067
Webrev: http://cr.openjdk.java.net/~akulyakh/8150067/test/serviceability/tmtools/jstat/GcCapacityTest.java.udiff.html

The test needs to be quarantined until its occasional failures, as reported by https://bugs.openjdk.java.net/browse/JDK-8149778, are analyzed

Best regards,
Alexander