Enable nova anti-affinity in two-node act-stdby job

Production deployments are recommended to run on active-standby
loadbalancer topology and with nova anti-affinity enabled for higher
level of availability. Job octavia-v2-act-stdby-dsvm-scenario-two-node
will test Octavia under such configuration.

Task: 40413
Story: 2007943

Change-Id: Iab24754bf6881671091a06047767f8b4dc8b5420
1 file changed