OSC plugin should be region/interface aware

This fixes the OSC plugin so that if region is specified or if the
interface is specified (public, internal, admin) then those will be
passed into the heat_client when instantiated.  Without this the
client will pick the endpoint for the first region returned instead of
the one specified.

Closes-Bug: #1556263
Change-Id: I9c15719e7711c93e7fd076d38d66011bb20f988d

heatclient/osc/plugin.py

@@ -33,8 +33,14 @@ def make_client(instance):
         API_VERSIONS)
     LOG.debug('Instantiating orchestration client: %s', heat_client)
 
+    endpoint = instance.get_endpoint_for_service_type(
+        API_NAME,
+        region_name=instance._region_name,
+        interface=instance._interface,
+    )
+
     client = heat_client(
-        endpoint=instance.get_endpoint_for_service_type('orchestration'),
+        endpoint=endpoint,
         session=instance.session,
         auth_url=instance._auth_url,
         username=instance._username,