Tune FRC trapped Bishop patch

Tune FRC trapped Bishop patch

now that fishtest can deal with FRC, retune this correction.

Add an additional fen to bench with cornered B and N.

passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 49672 W: 7358 L: 7082 D: 35232
Ptnml(0-2): 241, 4329, 15458, 4529, 279
https://tests.stockfishchess.org/tests/view/61d8b7bf9fea7913d9c63cb7

passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,3.00>
Total: 86688 W: 8308 L: 8007 D: 70373
Ptnml(0-2): 92, 4943, 32989, 5212, 108
https://tests.stockfishchess.org/tests/view/61d92dcb9fea7913d9c650ad

closes https://github.com/official-stockfish/Stockfish/pull/3884

Bench: 4326560