Tuned history reduction

Tuned history reduction

Value after a long Bayesian tuning, using a home-made classification approach.

STC
https://tests.stockfishchess.org/tests/view/5e7c7b16e42a5c3b3ca2eb66
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 45472 W: 8992 L: 8732 D: 27748
Ptnml(0-2): 795, 5276, 10352, 5500, 813

LTC
https://tests.stockfishchess.org/tests/view/5e7c8be7e42a5c3b3ca2eb75
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 22744 W: 3085 L: 2849 D: 16810
Ptnml(0-2): 156, 2090, 6658, 2298, 170

closes https://github.com/official-stockfish/Stockfish/pull/2597

Bench 5030855