Delete paired wall technologies.
“Rubble Materials” and “Geometric Masonry”, paired techs, could be researched by most civs. They had limited use, were incoherent with civ-specific art, and were researchable at wall-towers, at which points techs that affect walls make less sense.
As such, they are deleted.
Patch by: Nescio
Accepted By: borg-, wraitii
Differential Revision: https://code.wildfiregames.com/D2880