oslo.messaging allow dispatcher to restrict endpoint methods since
5.11.0 in I42239e6c8a8be158ddf5c3b1773463b7dc93e881, set with
LegacyRPCAccessPolicy explicitly to ensure it's compatible and
fix FutureWarning like:
"The access_policy argument is changing its default value to <class
'oslo_messaging.rpc.dispatcher.DefaultRPCAccessPolicy'> in version '?',
please update the code to explicitly set None as the value:
access_policy defaults to LegacyRPCAccessPolicy which exposes private
methods. Explicitly set access_policy to DefaultRPCAccessPolicy or
ExplicitRPCAccessPolicy.
Change-Id: I60dfaa09113ebf2460126c968e5839f1b6a4bda9
705a81a216