Fix for SSH method of OSTF tests

In SSH method of OSTF tests address of controller node is chosen
as the first from list of controller nodes.
It may not work when we have a few controller nodes (HA mode) and one
of controller nodes went away. Now controller node is chosen
from list of controller nodes online.

Closes-Bug: #1346864

Change-Id: I74801a352c4a96e1fa1c254fd49db19d6584b427
Merge "Fix for SSH method of OSTF tests"