MB-100 Make get_remote_cluster/0 faster.

get_remote_cluster/1 was removed since it's not used anywhere.

Change-Id: I42afd94b57b061abda9a52d047d8280b7e9f4eba
Reviewed-on: http://review.couchbase.org/27662
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>