Use stat_malus when decreasing stats
This patch applies stat_bonus when increasing and stat_malus when decreasing stats.
Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 133792 W: 34221 L: 33758 D: 65813
Ptnml(0-2): 477, 15764, 33959, 16211, 485
https://tests.stockfishchess.org/tests/view/654699f3136acbc5735256b2
Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 67374 W: 16912 L: 16523 D: 33939
Ptnml(0-2): 42, 7528, 18171, 7891, 55
https://tests.stockfishchess.org/tests/view/65474558136acbc5735263ab
closes https://github.com/official-stockfish/Stockfish/pull/4864
bench: 1114417