aosp_arm64: add the android-4.19-stable Image.gz prebuilt am: b068fe1bc8

Original change: https://googleplex-android-review.googlesource.com/c/kernel/prebuilts/4.19/arm64/+/11885398

Change-Id: If80530ac71ec4ea9c86938fe6af2601fb278e997
tree: 2368aa566cb205411d72160a6bdad37340de3efe
  1. .prebuilt_info/
  2. Image.gz