Delay collectd start

We need to make collectd container start in the same step as Gnocchi,
so that we avoid occasional connection problems with collectd deployed
without working Keystone and Gnocchi.

Change-Id: Ifce5d3a7395d9ddf99e2d9097f71a222e8c64487

docker/services/collectd.yaml

@@ -89,7 +89,7 @@ outputs:
               owner: collectd:collectd
               recurse: true
       docker_config:
-        step_3:
+        step_5:
           collectd:
             image: {get_param: DockerCollectdImage}
             net: host