Simplify away king infiltration.

STC :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 91438 W: 17496 L: 17438 D: 56504
Ptnml(0-2): 1573, 10711, 21067, 10790, 1563
https://tests.stockfishchess.org/tests/view/5e34812630ae32da08941d65

LTC :
LLR: 2.96 (-2.94,2.94) {-1.50,0.50}
Total: 40485 W: 5246 L: 5177 D: 30062
Ptnml(0-2): 289, 3818, 11976, 3812, 327
https://tests.stockfishchess.org/tests/view/5e354daee70d848499f6380c

closes https://github.com/official-stockfish/Stockfish/pull/2542

Bench: 5047825