MB-11156 Graceful failover checks same conditions as normal one.

Change-Id: I2ed9e654a563160425644ca035a191a53d7820a3
Reviewed-on: http://review.couchbase.org/39182
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>