Simplify doDeeperSearch
Passed simplification STC
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 92096 W: 23888 L: 23728 D: 44480
Ptnml(0-2): 336, 10796, 23608, 10988, 320
https://tests.stockfishchess.org/tests/view/694b6b9d572093c1986d6ae0
Passed simplification LTC
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 50064 W: 12789 L: 12598 D: 24677
Ptnml(0-2): 24, 5350, 14103, 5521, 34
https://tests.stockfishchess.org/tests/view/694d49aa572093c1986d7021
closes https://github.com/official-stockfish/Stockfish/pull/6493
Bench: 2494221