Remove rabbitmq max_retries

It was never clear was the purpose of this option.

For the RPC API point of view raising MessageDeliveryFailure is kind
of unexpected. For the Notification API, this is weird that when
application put retry=-1, the lib stop to retry only with rabbit.

So this change deprecates this option for removal.

Change-Id: I4ac3a062426418276c96e1745d1c96a8525c36da

oslo_messaging/_drivers/impl_rabbit.py

@@ -156,6 +156,7 @@ rabbit_opts = [
                     'Default is 30 seconds.'),
     cfg.IntOpt('rabbit_max_retries',
                default=0,
+               deprecated_for_removal=True,
                deprecated_group='DEFAULT',
                help='Maximum number of RabbitMQ connection retries. '
                     'Default is 0 (infinite retry count).'),