Remove special case for NoGroupGrouping when building negative queries

Back in 06cb52d and ac64840b, when moving the SPARQL-formatting code from
get_query_for_items_for_property_nega|positive to the Line objects,
we introduced a special case for NoGroupGrouping.

The reason was that both the grouping exclusion and the column exclusion
use a MINUS construct, and we were trying to use only one with a UNION.

But since both exclusion statements are independent,
we can have two MINUS statements one after the other.

This removes a special case in get_query_for_items_for_property_negative,
and the dual nega|postive_query_filter_out_fragment in the Line objects,
which only existed for overloading in NoGroupGrouping.

Bug: T251008