Merge "Introduce a Soong config variable to flip to ART Module sources when prebuilts are preferred by default." am: ba62030943 am: 05b65151d2

Original change: https://android-review.googlesource.com/c/device/generic/art/+/1513781

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I4638c449d15b24d3b6adcdc15f39ae7c5b981eba