Convert println in test to SLF4j

Not sure why we used printlns for debugging. We should just switch to slf4j and then control the output with the log4j.properties file. We could then drop the special usage of the muteTestLogs system property.

Part of this should be to sort out what's going on with controlling log4.properties from maven. That creates problems apparently (attempted to do that on a different ticket and caused hadoop/spark stuff to fail)