simplify razoring
Passed Non-regression STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 93056 W: 24215 L: 24054 D: 44787
Ptnml(0-2): 364, 11085, 23470, 11244, 365
https://tests.stockfishchess.org/tests/view/67883a5d3b8f206a2696b804
Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 66564 W: 16971 L: 16794 D: 32799
Ptnml(0-2): 56, 7403, 18192, 7570, 61
https://tests.stockfishchess.org/tests/view/6789ffa78082388fa0cbfe95
closes https://github.com/official-stockfish/Stockfish/pull/5788
bench 1500649