VOLTHA atest gives inconsistent results

VOLTHA's atest framework brings up k8s with VOLTHA, ONOS, and Ponsim, and runs simple tests to authenticate the RG, get a DHCP address, and check the subscriber flows.  However the atests often give inconsistent results using the same set of containers.  Sometimes all tests will fail, sometimes they will all pass, and sometimes a couple of tests will pass and the rest fail.