Add healthcheck to ironic_pxe_http

This was missing from the undercloud

Change-Id: Iec2ed5bd7ca3d9c1f601b6c3940de77ab80525b5

deployment/ironic/ironic-pxe-container-puppet.yaml

@@ -134,6 +134,8 @@ outputs:
             privileged: false
             security_opt: 'label=disable'
             restart: always
+            healthcheck:
+              test: /openstack/healthcheck
             volumes:
               list_concat:
                 - {get_attr: [ContainersCommon, volumes]}