Merge "Update gsi_arm64 to use gsi_product.mk & gsi_system_ext.mk" am: 3e96647d29 am: 00dc5a2ffd am: 907f001797

Original change: https://android-review.googlesource.com/c/device/generic/common/+/1556538

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ica6985f3e8afb98122a8129c7ae102df3c639df2