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

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

Change-Id: Ic7848dbe43700cb06fac0ca25683f086a4d4e3a5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>