Drop fedmsg_qa_network concept

I don't think this is needed any more. openQA publishes natively
to fedora-messaging these days, and these groups never have done
anything there. ResultsDB still publishes to fedmsg, it seems,
but the new instances were not added to these groups and I don't
think we need/want to do that, we should just make sure they
have the necessary access via other more widely-used groups if
anything. (It seems like the restrictions these groups used to
affect have been - possibly temporarily - removed entirely at
present, but we can figure out any necessary changes there if the
restrictions are restored).

Signed-off-by: Adam Williamson <awilliam@redhat.com>

filter_plugins/fedmsg.py

@@ -9,7 +9,7 @@ def invert_fedmsg_policy(groups, vars, env):
     """
 
     if env == 'staging':
-        hosts = groups['all'] + groups['staging'] + groups['fedmsg_qa_network_stg']
+        hosts = groups['all'] + groups['staging']
     else:
         hosts = [h for h in groups['all'] if h not in groups['staging']]