MB-10243: increase retry in rebalance_reached

Change-Id: I33c5e368f7bb849f5a6a06f4ca3b582f194de480
Reviewed-on: http://review.couchbase.org/33733
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>