Migrate shell-as to platform_testing/utils am: a2962f57d5 am: ceb89e71c4 am: 40a8ce9a8c am: 990dfff702 am: f0eb49acac am: df5a57142f

Original change: https://googleplex-android-review.googlesource.com/c/platform/platform_testing/+/24211864

Change-Id: I58a786350b99c891a0d40f47ef1ea4cb849f6810
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>