MB-10318 evictionPolicy always defaults to valueOnly.

Change-Id: Iaa4308aa7dc0f76efb1d33e106668d961084e8d4
Reviewed-on: http://review.couchbase.org/34215
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>