Implement smoother reduction in time management
Implement smoother time reduction in time management by replacing a conditional
assignment with a continuous sigmoid-based function. The updated logic employs
a sigmoid-like function for a more gradual adjustment.
Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 64448 W: 16838 L: 16492 D: 31118
Ptnml(0-2): 145, 7214, 17207, 7466, 192
https://tests.stockfishchess.org/tests/view/6829dc046ec7634154f99fba
Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 407340 W: 104458 L: 103408 D: 199474
Ptnml(0-2): 196, 42281, 117664, 43335, 194
https://tests.stockfishchess.org/tests/view/6829fe1b6ec7634154f9a036
closes https://github.com/official-stockfish/Stockfish/pull/6091
No functional change