CBQE-309: Fix swaprebalance tests to work against cluster_run

Change-Id: I104b6bbb831ba0827b3c32b6ad2993311da78521
Reviewed-on: http://review.couchbase.org/23785
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>