Migrate to cargo_embargo. am: d939d4fef1 am: bd7eb5a76c am: b8f0366d8a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rand_core/+/2824510

Change-Id: Ia53033a4e85a72db7b44a4a29e9547a7b9751240
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>