[Gameplay A27] - Han fixes:
- Remove crossbow_training.json from the Han academy
- Adjust the cost of poison arrows and poison blades so that the ranged upgrade should be the one to cost metal, since ranged units currently dominate most battles.
- Reduce the obstruction area of rice paddies so that they are easier to place.
Patch by: @real_tabasco_sauce
Accepted by: @chrstgtr, @wowgetoffyourcellphone
Differential Revision: https://code.wildfiregames.com/D4873