Remove threatenedByPawn from rook threat
Can be simplified away.
Passed STC:
https://tests.stockfishchess.org/tests/view/65a3fa4179aa8af82b96face
LLR: 2.92 (-2.94,2.94) <-1.75,0.25>
Total: 30592 W: 7903 L: 7674 D: 15015
Ptnml(0-2): 96, 3590, 7711, 3787, 112
Passed LTC:
https://tests.stockfishchess.org/tests/view/65a42b9a79aa8af82b96fe88
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 73656 W: 18382 L: 18212 D: 37062
Ptnml(0-2): 47, 8287, 19981, 8475, 38
closes https://github.com/official-stockfish/Stockfish/pull/4993
Bench: 1430061