Migrate to cargo_embargo. am: f78d645463

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/grpcio-compiler/+/2832422

Change-Id: Icff8a883f7f897f09c30d142e561b599225c630e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>