CBQE-927: fix verification in online_upgrade_rebalance_in_with_ops

Change-Id: I96f0bc2a7dce4674e8155c4c40bad8eb0a34984d
Reviewed-on: http://review.couchbase.org/24816
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>