Fix key generation for caching

With a new major version of decorate, the list of args may be non-empty
for the first time, exposing some issue in our handling. Ignore them
for now in order to unblock gating.

Task: 43007
Change-Id: Ia4e71a5ab02516a8ef40a94590b5c9092eab5fa5
(cherry picked from commit d0d4d8bc64)

openstack/cloud/openstackcloud.py

@@ -331,7 +331,8 @@ class _OpenStackCloudMixin:
             name_key = '%s:%s' % (self.name, namespace)
 
         def generate_key(*args, **kwargs):
-            arg_key = ','.join(args)
+            # TODO(frickler): make handling arg keys actually work
+            arg_key = ''
             kw_keys = sorted(kwargs.keys())
             kwargs_key = ','.join(
                 ['%s:%s' % (k, kwargs[k]) for k in kw_keys if k != 'cache'])