Add network verification to CI tests in thread_5

After deploying a HA cluster we need to be sure
that cluster is ready and network is working properly
before making a snapshot which is used
for all next tests in the thread.

Change-Id: Id34a0153eff14fcde56fb1939ddbab14bbd6457a
Closes-Bug: #1289297
(cherry picked from commit a379af4c5ca38fef7bf4d7b35abc45034a533791)