Adjust ButterflyHistory decay parameter

Adjust ButterflyHistory decay parameter

passed STC:
LLR: 2.98 (-2.94,2.94) <-0.50,2.50>
Total: 26680 W: 6807 L: 6593 D: 13280
Ptnml(0-2): 73, 3007, 6989, 3175, 96
https://tests.stockfishchess.org/tests/view/6174094e6ce927be32558441

passed LTC:
LLR: 2.98 (-2.94,2.94) <0.50,3.50>
Total: 21104 W: 5403 L: 5185 D: 10516
Ptnml(0-2): 8, 2160, 6001, 2372, 11
https://tests.stockfishchess.org/tests/view/61744927351812fe5f969864

closes https://github.com/official-stockfish/Stockfish/pull/3761

Bench: 6334068