Do not use async with zl restarter playbook

Running this playbook on the puppetmaster we consistently run into ssh
failures due to async reconnecting periodically and network issues
between hosts. We can address this by starting a single connection
without async and polling on that which appears to be the default
wait_for behavior. Testing of this seems to indicate it is more
reliable.

Change-Id: Iec72e2c0d099c0e28bc4b4b48608a03b3e66b4c0

playbooks/restart_zuul_launchers.yaml

@@ -10,8 +10,6 @@
       become_user: zuul
 
     - name: Wait for (3h10m) to stop zuul-launcher
-      async: 11400
-      poll: 60
       wait_for:
         path: /var/run/zuul-launcher/zuul-launcher.pid
         state: absent