The Masakari job uses 4 nodes and defaulted to a quite bulky
and not really supported config (MariaDB and RMQ on 4 nodes).
This change slims it down so that we test only HA of Masakari
and hacluster. The other services are deployed single-node.

Additionally, simplify the network group (it does not affect any
other job, the logic was simply overdone there).

Change-Id: I74b315443f79d0d7780907fc785e1a29759c1803