DO NOT MERGE: Add androidx prebuilt TEST_MAPPING file to tm-dev am: 1e4e9e1c90 am: 0ac66ad209

Original change: https://googleplex-android-review.googlesource.com/c/platform/prebuilts/sdk/+/20264551

Change-Id: I793cab8b26371ea5d07ad89c79e274ac2ff1116f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>