Improve palm rejection accuracy for 3+ fingers scenarios on kohaku

1. Update a new model trained with 3+ fingers data
2. Change the threshold to balance the performance between palms
and fingers

Bug: 198472780
Test: n/a (taken from upstream)
Merged-In: Ibc521a2b343cf56940df16ad8e213e3a0d888435
Change-Id: Ibc521a2b343cf56940df16ad8e213e3a0d888435
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3362772
Reviewed-by: Rob Schonberger <robsc@chromium.org>
Commit-Queue: Jing Wang <jiwan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#959002}
(cherry picked from commit 9b7296bd7f90726c0621dfc2d59780feed206bc1)
5 files changed