Remove unused @show_only_completed from view
Remove unused @show_only_completed from view

Now there's no difference in behavior. In both cases we sort by
completed_at in the second column of the orders page.

lin-d-hop/openfoodnetwork,Matt-Yorkley/openfoodnetwork,mkllnk/openfoodnetwork,lin-d-hop/openfoodnetwork,Matt-Yorkley/openfoodnetwork,mkllnk/openfoodnetwork,openfoodfoundation/openfoodnetwork,openfoodfoundation/openfoodnetwork,Matt-Yorkley/openfoodnetwork,openfoodfoundation/openfoodnetwork,lin-d-hop/openfoodnetwork,mkllnk/openfoodnetwork,lin-d-hop/openfoodnetwork,openfoodfoundation/openfoodnetwork,Matt-Yorkley/openfoodnetwork,mkllnk/openfoodnetwork