RFR: Instability in JFR test TestThreadCpuTimeEvent

[Robin Westberg]

Hi all,

Please review this change that makes the test case TestThreadCpuTimeEvent more stable. It was possible for the test to fail if the machine executing the test is very overloaded.

Issue: https://bugs.openjdk.java.net/browse/JDK-8205103 <https://bugs.openjdk.java.net/browse/JDK-8205103>
Webrev: http://cr.openjdk.java.net/~rwestberg/8205103/webrev.00/ <http://cr.openjdk.java.net/~rwestberg/8205103/webrev.00/>
Testing: open/test/jdk/jdk/jfr/event/runtime/*

Best regards,
Robin