[IR plugin] Ensure auto ssh key exchange in the test host

Tests executed on tripleo setups require ssh key exchange to connect
from the test host to itself

Change-Id: I1862bc2e5269ea6f269e2a17e127957f7d279849

infrared_plugin/roles/tobiko-ir-before-run/tasks/main.yaml

@@ -5,3 +5,8 @@
     source {{ stackrc_file }}
     openstack quota set --{{ item.key }} {{ item.value }} $OS_PROJECT_NAME
   with_dict: "{{ quota | default({}) }}"
+
+- name: ensure auto ssh key exchange in test host
+  shell: |
+    ssh -o PasswordAuthentication=no $(whoami)@localhost hostname || cat ~/.ssh/id_*.pub >> ~/.ssh/authorized_keys
+  ignore_errors: yes