chore(test): make sure to print the stacktrace in test logs (#2399)

Author: igorbernstein2

google-cloud-bigtable/src/test/resources/logging.properties

@@ -7,6 +7,6 @@ java.util.logging.ConsoleHandler.level = INFO
 
 java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
 # time [level] loggerName: message
-java.util.logging.SimpleFormatter.format=%1$tT [%4$-7s] %2$s: %5$s%n
+java.util.logging.SimpleFormatter.format=%1$tT [%4$-7s] %2$s: %5$s %6$s%n