Only do less LMR in the root

[kevlu8]

Elo   | 3.70 +- 2.87 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | 2.90 (-2.25, 2.89) [0.00, 5.00]
Games | N: 14932 W: 3527 L: 3368 D: 8037
Penta | [48, 1703, 3806, 1860, 49]

https://ob.int0x80.ca/test/625/

Elo   | 2.23 +- 2.30 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=128MB
LLR   | 1.79 (-2.25, 2.89) [0.00, 5.00]
Games | N: 21454 W: 4918 L: 4780 D: 11756
Penta | [22, 2469, 5604, 2613, 19]

https://ob.int0x80.ca/test/626/

Bench: 4182126