Reduce material imbalance for drop variants

Reduce material imbalance for drop variants

crazyhouse STC
LLR: 2.96 (-2.94,2.94) [0.00,10.00]
Total: 6889 W: 3445 L: 3246 D: 198
http://www.variantfishtest.org:6543/tests/view/5fe880736e23db221d9e96db

crazyhouse LTC
LLR: 2.95 (-2.94,2.94) [0.00,10.00]
Total: 10937 W: 5394 L: 5138 D: 405
http://www.variantfishtest.org:6543/tests/view/5fe886dc6e23db221d9e96de

minishogi STC
LLR: 2.98 (-2.94,2.94) [-10.00,5.00]
Total: 2499 W: 1275 L: 1224 D: 0
http://www.variantfishtest.org:6543/tests/view/5fe8d0296e23db221d9e96e0