Subsume prebuilt_etc through prebuilt_file usage am: 3dc924bdb4 am: 6234e86c39 am: a4ecd7a1d0 am: c7d5439fbb

Original change: https://android-review.googlesource.com/c/platform/build/bazel/+/1980706

Change-Id: If2c04fac88fdf0e41645dabcbf460cfdb16de08f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>