CBD-762: fix check_tap_connect

It's broken since we use couchbase 1.8 in samples.
See f75b10e3a11e41b28568dde028a4284efdab084d for details.

Change-Id: I3f09b2730ae5eb5a264966508bfae9cae1f3495a
Reviewed-on: http://review.couchbase.org/23915
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>