Use BatchMode to check whether host is accessible via SSH

If password authentication is not disabled on the server, we may be
prompted for a password if the Kayobe Ansible user doesn't exist or
isn't configured for passwordless authentication.

By using BatchMode, the ssh command can fail quickly and proceed to
create the Kayobe Ansible user using the bootstrap user.

Change-Id: If22ed34dc4b6e87f8cf76c302948c955bddf2bc5

ansible/kayobe-ansible-user.yml

@@ -14,7 +14,7 @@
   tasks:
     - name: Check whether the host is accessible via SSH
       local_action:
-        module: command ssh -p {{ ssh_port }} {{ ssh_user }}@{{ ssh_host }} hostname
+        module: command ssh -o BatchMode=yes -p {{ ssh_port }} {{ ssh_user }}@{{ ssh_host }} hostname
       failed_when: false
       changed_when: false
       register: ssh_result

releasenotes/notes/ssh-batchmode-cda7a4ed63006378.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Uses BatchMode to check whether a host is accessible via SSH. This prevents
+    Kayobe from hanging on a password prompt when password authentication is
+    enabled on the host and the Kayobe Ansible user is not yet configured.