logs thread id for integration tests

This change is already present in the main branch.  Pulling it back to
2.1 as its very useful for debugging some problems to know which thread
logged a message.

Author: keith-turner

test/src/main/resources/log4j2-test.properties

@@ -25,7 +25,7 @@ appender.console.type = Console
 appender.console.name = STDOUT
 appender.console.target = SYSTEM_OUT
 appender.console.layout.type = PatternLayout
-appender.console.layout.pattern = %d{ISO8601} [%c{2}] %-5p: %m%n
+appender.console.layout.pattern = %d{ISO8601} %T [%c{2}] %-5p: %m%n
 
 logger.01.name = org.apache.accumulo.core
 logger.01.level = debug