[Win64ARM] Remove nacl_loader_unittests from win-arm64-rel

The test suite is not available on arm64.

Bug: 1383380
Change-Id: If2bb79a9ee9c812165eaacc87448fa8fc44d8eaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4348027


Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Kuan Huang <kuanhuang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1118936}