limit dynamic reduction.
fixes https://github.com/official-stockfish/Stockfish/issues/6280
prevents probcut from extending depth as analyzed here:
https://github.com/official-stockfish/Stockfish/pull/6254#issuecomment-3239144280
passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 86688 W: 22591 L: 22426 D: 41671
Ptnml(0-2): 305, 10125, 22311, 10306, 297
https://tests.stockfishchess.org/tests/view/68b418ab467ff96994ae4cd5
passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 82914 W: 21287 L: 21130 D: 40497
Ptnml(0-2): 39, 8959, 23305, 9114, 40
https://tests.stockfishchess.org/tests/view/68b47ffa78ed7a752a9e8f36
closes https://github.com/official-stockfish/Stockfish/pull/6286
Bench: 2787731
Co-Authored-By: xu-shawn <50402888+xu-shawn@users.noreply.github.com>