MB-100 use longer timeout for raw_stats

Change-Id: I09dd49c051141c03899d2ecb63e0ae9403c528fa
Reviewed-on: http://review.couchbase.org/33409
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>