Simplify Internal Iterative Reductions (IIR) Condition
Passed STC non-reg:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 75840 W: 19367 L: 19192 D: 37281
Ptnml(0-2): 186, 8837, 19710, 8990, 197
https://tests.stockfishchess.org/tests/view/6a0b02ba6524d21ee79b8685
Passed LTC non-reg:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 166920 W: 42039 L: 41967 D: 82914
Ptnml(0-2): 78, 18155, 46919, 18233, 75
https://tests.stockfishchess.org/tests/view/6a0c98fb6524d21ee79b8875
Passed VTC non-reg:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 46390 W: 11914 L: 11729 D: 22747
Ptnml(0-2): 8, 4543, 13911, 4722, 11
https://tests.stockfishchess.org/tests/view/6a143877818cacc1db0ac7c5
closes https://github.com/official-stockfish/Stockfish/pull/6861
Bench: 2814421