CBQE-0 fix monitor DCP rebalance.

Change-Id: I8b9991866a6638cbab3d298504bc1a06376f0206
Reviewed-on: http://review.couchbase.org/43490
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>