When generating keys and sharing them between nodes
in a multinode env it is important that task which
generates keys is finished before trying to use these
keys on another node.
The PR splits the Ansible block into two blocks and
makes sure the playbook deploy-env is run with the linear
strategy. Thus we can be sure that keys are first generated
on all affected nodes and only then are used to setup
tunnels and passwordless ssh.
Change-Id: I9985855d7909aa5365876a24e2a806ab6be1dd7c
a5f6eb6ed4