Remove unused Android.mk am: 1f8ef931c8 am: bf9f19ab69

Original change: https://android-review.googlesource.com/c/platform/tools/test/graphicsbenchmark/+/2826052

Change-Id: I2ab51086a25e67230473d07af5f3d995ac2c7a00
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>