Simplify depth increase condition further
Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 51232 W: 13560 L: 13351 D: 24321
Ptnml(0-2): 183, 6075, 12920, 6226, 212
https://tests.stockfishchess.org/tests/view/679d7b2b0774dfd78deb043f
Passed Non-regression LTC (v. #5827):
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 172398 W: 44108 L: 44042 D: 84248
Ptnml(0-2): 122, 19207, 47489, 19245, 136
https://tests.stockfishchess.org/tests/view/679d7fb10774dfd78deb05d2
Passed Non-regression VLTC (v. #5827):
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 388540 W: 99314 L: 99464 D: 189762
Ptnml(0-2): 89, 40454, 113350, 40272, 105
https://tests.stockfishchess.org/tests/view/679da3be0774dfd78deb0ad4
closes https://github.com/official-stockfish/Stockfish/pull/5846
Bench: 2688175