Remove unused pubsub stuff

appengine/gce-backend/catalog.py

Index: appengine/gce-backend/catalog.py
diff --git a/appengine/gce-backend/catalog.py b/appengine/gce-backend/catalog.py
index 3d705f98ffd35469f697b1fdac04b6c51c20a585..971afcb072c4655b02d6abec86b3495242be4758 100644
--- a/appengine/gce-backend/catalog.py
+++ b/appengine/gce-backend/catalog.py
@@ -19,7 +19,6 @@ import instances
 import instance_group_managers
 import metrics
 import models
-import pubsub
 
 
 def get_policies(key, service_account):
@@ -35,8 +34,6 @@ def get_policies(key, service_account):
           'key': 'key',
           'value': key.urlsafe(),
       },
-      'backend_project': pubsub.get_machine_provider_topic_project(),
-      'backend_topic': pubsub.get_machine_provider_topic(),

[ryanmartens, 2016/11/04 14:02:52]

We should probably update the comment in the Policies message to capture the
changes regarding the communication with the GCE Backend specifically:
https://github.com/luci/luci-py/blob/master/appengine/components/components/m...

[ryanmartens, 2016/11/04 14:02:52]

Also, are you planning on pulling out the notification on this channel from
machine provider in another CL, or should you combine it with this one?
https://github.com/luci/luci-py/blob/884aff5a309833270d9243e919e19a4a35ed143a...

[smut, 2016/11/04 21:09:21]

Everything there is technically true, MP will still communicate with its
backends on a backend_topic if provided.

[smut, 2016/11/04 21:09:21]

Right now backend notification is optional, if backend_topic is present. I'm
guessing we will want to remove this altogether, but I'm not 100% sure that no
backend will use it. I'll save MP and Policies changes for a separate CL if I
completely remove support for backend_topic.

       'machine_service_account': service_account,
       'on_reclamation': 'DELETE',
   }