Add Android-U system images to android-sdk-packager

Bug: 1439892
Change-Id: Icc49df25253dd2da02452cd48b554eea97e87759
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4506413
Reviewed-by: Haiyang Pan <hypan@google.com>
Commit-Queue: Gabrielle Lau <gabriellelau@google.com>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1139710}
NOKEYCHECK=True
GitOrigin-RevId: 0cc34e0a81be0fa350578a1d60b47274bd832a3d