Simplify Tweak late move reductions at root.

[xoto10]

Revert change from Jan 15.

STC 10+0.1 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 65135 W: 12543 L: 12436 D: 40156
Ptnml(0-2): 1090, 7618, 14947, 7623, 1136
https://tests.stockfishchess.org/tests/view/5e334016708b13464ceea32e

LTC 60+0.6 :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 17768 W: 2286 L: 2191 D: 13291
Ptnml(0-2): 128, 1602, 5273, 1679, 140
https://tests.stockfishchess.org/tests/view/5e34011e57e1ecae66ec2aab

Bench 4914050

[adentong]

I remember this one took 180k games to pass. Probably a good idea to revert.

[vondele]

@adentong needing many games means that the estimated Elo is more near the middle of the interval, and that the error bars for that estimate are relatively small. However, the SPRT bounds are still part of the Elo range.

[vondele]

Thanks!