Delete select_commerce_data.sql

Once vitessio/website#656 and vitessio/website#646 have been committed to adjust the Vitess docs this file should be removed as it was confirmed to be redundant to https://github.com/vitessio/vitess/blob/master/examples/common/select_commerce_data.sql.

Signed-off-by: hallaroo <marla@planetscale.com>