Remove unused Android.mk file am: 81d616b19d am: f0f29e1818 am: 82729b5f9b

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

Change-Id: I0526290aef7cbef69d33fc7c2fc5a449948d4f15
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>