ISPN-4372 Map/Reduce performance is dependent on cache value size

Master only. Do not integrate - yet. See https://mojo.redhat.com/docs/DOC-967886 and https://issues.jboss.org/browse/ISPN-4372 for more details. 
Could not find where exactly but if it is internal API javadoc it is fine as we still use the concept of it - we just set it to constant value of 1000