SimpleTwoNodesMapReduceTest.testInvokeMapperCancellation with the new log4j2 configuration

When moving the log4j2 configuration files for ISPN-6255, I also made the file appender asynchronous. Because the async appender catches InterruptionException s and resets the thread interruption status, this affected SimpleTwoNodesMapReduceTest.testInvokeMapperCancellation, and it's failing almost every time.