Fix passing keystone token to neutronclient instance

Neutron client expects token to be passed as token= argument, while
neutron-metadata-agent passes auth_token= instead. This effectively makes the
client to authenticate against keystone each time it's instantiated. In
neutron-metadata-agent case, it means 'each time a client sends a metadata
request.'

The issue results in high cpu utilization on keystone side when simultaneously
invoking multiple nova instances with cloud-init.

Change-Id: I2a31f9c0c3cfa915975ecc53d71168a3895528d8
Closes-Bug: 1274487
(cherry picked from commit 3799efe792)

neutron/agent/metadata/agent.py

@@ -80,7 +80,7 @@ class MetadataProxyHandler(object):
             auth_url=self.conf.auth_url,
             auth_strategy=self.conf.auth_strategy,
             region_name=self.conf.auth_region,
-            auth_token=self.auth_info.get('auth_token'),
+            token=self.auth_info.get('auth_token'),
             endpoint_url=self.auth_info.get('endpoint_url'),
             endpoint_type=self.conf.endpoint_type
         )

neutron/tests/unit/test_metadata_agent.py

@@ -99,7 +99,7 @@ class TestMetadataProxyHandler(base.BaseTestCase):
                 auth_url=FakeConf.auth_url,
                 password=FakeConf.admin_password,
                 auth_strategy=FakeConf.auth_strategy,
-                auth_token=None,
+                token=None,
                 endpoint_url=None,
                 endpoint_type=FakeConf.endpoint_type)
         ]