Do more full window searches

Do more full window searches

Remove the value < beta condition for doing full window searches.
As an added bonus the condition for full-window search is now much
more similar to other fail-soft engines.

Passed STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 244608 W: 62286 L: 62294 D: 120028
Ptnml(0-2): 758, 28772, 63214, 28840, 720
https://tests.stockfishchess.org/tests/view/64d72d365b17f7c21c0e6675

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 311460 W: 78909 L: 78985 D: 153566
Ptnml(0-2): 129, 33959, 87656, 33831, 155
https://tests.stockfishchess.org/tests/view/64dca2265b17f7c21c0ee06c

closes https://github.com/official-stockfish/Stockfish/pull/4755

Bench: 1624221