how to find JAR: /home/hadoop/contrib/streaming/hadoop-streaming.jar
The Hadoop streaming jar is still available in the latest release of EMR Hadoop. Starting with EMR release 4.0.0 it can be found at /usr/lib/hadoop-mapreduce/hadoop-streaming.jar.
Another good resource for differences between versions can be found at http://docs.aws.amazon.com/ElasticMapReduce/latest/ReleaseGuide/emr-release-differences.html.
For the variable, HADOOP_STREAMING, obtaining the path is a bit more complicated depending on the HDP you are using.
Search for where it is located via command:find / -name 'hadoop-streaming*.jar'