[Stateless SG] Ensure replies won't work without ingress rule

This patch extends existing
test_connectivity_between_vms_using_different_sec_groups
in the way that for stateless SG rules it makes sure that replies from
server to client will not work without explicity add SG rule which will
allow ingress traffic on the ephemeral ports' range.

Change-Id: I940678c15b65552634096ea3e72888b5bf830912
1 file changed