Simplify smallnet threshold
remove pawncount
Passed STC non-reg:
https://tests.stockfishchess.org/tests/view/665e4548fd45fb0f907c80d5
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 60896 W: 15710 L: 15518 D: 29668
Ptnml(0-2): 149, 7145, 15660, 7353, 141
Passed LTC non-reg:
https://tests.stockfishchess.org/tests/view/665e4c52fd45fb0f907c815f
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 58068 W: 14773 L: 14590 D: 28705
Ptnml(0-2): 16, 6368, 16090, 6537, 23
closes https://github.com/official-stockfish/Stockfish/pull/5349
Bench: 1343156