Distributed statisics number varies among nodes (distributed workmanager

Reproducing test in https://github.com/LittleJohnII/wildfly/tree/eap7-495

# build WFLY first
cd testsuite/integration/basic
mvn clean test -Dtest='Dwm*TestCase' -Djboss.server.config.file.name=standalone-ha.xml -DtrimStackTrace=false -Darquillian.launch=distributed-group

All the cases contain checks for distributed statistics and in some cases, these show unexpected numbers (usually, at least one test method fails for each case). For example, scheduling two work instances would produce distributed stats =2 for node1 and =3 for node 2.

I already mentioned this to smaestri@redhat.com, so this is mainly a tracker.

This is a minor hamper to test writing for EAP7-495, but doesn't block it (not severe enough) - if this isn't resolved before I create a PR for tests, I'll have to comment out the distributed statistics checks.