LUCI: Add armv8 qemu builder am: 501a89cd3e

Original change: https://android-review.googlesource.com/c/platform/art/+/2975133

Change-Id: I2a0201f700510effc5a52138a05d2cbdc2ab4003
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>