Migrate to cargo_embargo. am: 5f402752c8 am: 5bf8497214 am: f8c59e9ac0

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/futures/+/2829796

Change-Id: Ic7f930bbb833e40d2f694ca0dc6c485e55a39b01
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>