test/rgw/notification: use real ip address instead of localhost

test/rgw/notification: use real ip address instead of localhost

based on that comment:
https://tracker.ceph.com/issues/67206#note-6
the address used by the endpoint is taken as the real IP address of the
host where the test script is running and not localhost.

we also changed the rabbitmq-server conf to allow "guest"
user to connect over non localhost address

Fixes: https://tracker.ceph.com/issues/67206
Signed-off-by: Yuval Lifshitz <ylifshit@ibm.com>