Remove penalty for knight when few enemy pawns

Tested in standard mode at STC and no-regression
mode at LTC:

STC
LLR: 2.97 (-2.94,2.94) [-1.50,4.50]
Total: 19503 W: 3502 L: 3349 D: 12652

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 67474 W: 9974 L: 9921 D: 47579

bench: 8331217