No longer use flattened APEX packages in ART Buildbot targets. am: d2fbc95b18 am: f840ecb6cb am: 9ee9d9762f am: c177f7d3a9 am: ffe8f2d4b4

Original change: https://android-review.googlesource.com/c/device/generic/art/+/1823302

Change-Id: Ib6c90afd2c68c141ba5a40160123c879db2dfc0b