Remove 8th Subnetwork

Description

Due to the early FEN skipping in our training process, there is a possibility that the 8th subnetwork (29-32 pieces) is no longer useful.

Branches

• 38e0cc7b-1

Tests

Test #1

Stockfish Testing Framework

Result

Stopped

Stats

LLR: 0.56 (-2.94,2.94) <-1.75,0.25>
Total: 8544 W: 2242 L: 2202 D: 4100
Ptnml(0-2): 31, 968, 2239, 998, 36

Stopped early as it has little sense to test with non-regression bounds.

Test #2

Stockfish Testing Framework

Result

Failed

Stats

LLR: -2.92 (-2.94,2.94) <0.00,2.00>
Total: 295104 W: 76702 L: 76526 D: 141876
Ptnml(0-2): 1063, 34853, 75553, 35011, 1072

Elo difference is likely neutral, suggesting that the 8th subnetwork could be removed to reduce the NNUE file size by ~49KiB (BigNet).