MB-8604 changed REST api url in cluster_connect

...for default bucket creation call to adhere to the
changes made for MB-7720

Change-Id: I488deb852acf188c8e4ff6dfc1e379c6f96f633a
Reviewed-on: http://review.couchbase.org/27430
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>