Simplify fail high reduction formula
Passed STC:
LLR: 2.97 (-2.94,2.94) <-1.75,0.25>
Total: 165792 W: 42849 L: 42768 D: 80175
Ptnml(0-2): 512, 19499, 42800, 19566, 519
https://tests.stockfishchess.org/tests/view/695cdd95912b7ff140de60c2
Passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 80448 W: 20619 L: 20459 D: 39370
Ptnml(0-2): 47, 8693, 22596, 8829, 59
https://tests.stockfishchess.org/tests/view/695f7e84ca95f52e4b852536
closes https://github.com/official-stockfish/Stockfish/pull/6535
bench: 2050811