Remove unused Android.mk file am: 81d616b19d am: 2a26b9490f am: 4ecf403995

Original change: https://android-review.googlesource.com/c/platform/tools/tradefederation/contrib/+/2854378

Change-Id: I94d86b792da6d421b78b6483f3ff8165f183c3d1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>