correctly hide graceful failover checkbox

Change-Id: I3be0f17385cabe102aba7acbab486671105c00f4
Reviewed-on: http://review.couchbase.org/35176
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>