Remove unused Android.mk file am: 81d616b19d

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

Change-Id: Icbb99ef320962bda6cb55f6df4fa9f15d064e4ea
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>