Simplify TT cutoff conthist updates
Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 86304 W: 22251 L: 22084 D: 41969
Ptnml(0-2): 250, 10214, 22123, 10249, 316
https://tests.stockfishchess.org/tests/view/67db60cd8c7f315cc372aae7
Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 199158 W: 50655 L: 50617 D: 97886
Ptnml(0-2): 103, 21579, 56182, 21607, 108
https://tests.stockfishchess.org/tests/view/67dcdc5b8c7f315cc372ac12
closes https://github.com/official-stockfish/Stockfish/pull/5945
Bench: 2069191