Fix the path to the system image for Android 31 arm64.

Bug: 1362902
Change-Id: I6fc9c70e57d11ac38a18770e85de9547d7a1f53b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3899854
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Haiyang Pan <hypan@google.com>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1048130}
NOKEYCHECK=True
GitOrigin-RevId: a7d4cb2931440a4ee5f444b212ab2fb08e36902c