CBQE-0: Update memcached error code in smoke tests

Change-Id: I861da43cb583b20d47362c588b7393de8fef38cf
Reviewed-on: http://review.couchbase.org/41563
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Reviewed-by: Meenakshi Goel <meenakshi.goel@globallogic.com>
Tested-by: Meenakshi Goel <meenakshi.goel@globallogic.com>