MB-11775: anticipate rebalance stop while verifying replicas

This merges reverted commit back.

Change-Id: I9fd370e59562b8e8a07a1ef383c442ccf4b7fd1e
Reviewed-on: http://review.couchbase.org/39756
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>