jmx-dev RFR 8031559: javax/management/monitor/StartStopTest.java fails intermittently

[Jaroslav Bachorik]

Please, review the following test change.

Issue : https://bugs.openjdk.java.net/browse/JDK-8031559
Webrev: http://cr.openjdk.java.net/~jbachorik/8031559/webrev.00

The test fails intermittently - the "called" flag it is using to 
indicate that a workload was successfully processed is not volatile or 
synchronized and is set from a different thread than the one which 
checks it. This can lead to race conditions making the test fail. The 
other test improvement is to honor the "test.timeout.factor" property to 
properly scale any timeouts used in the test.

Thanks,

-JB-