CBQE-1082 modify kv test spec for week long run

Change-Id: I0c2ec25c3a2bd6ac7fb5fba98fb7b7404308c72d
Reviewed-on: http://review.couchbase.org/26490
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Chisheng Hong <chisheng@couchbase.com>