Migrate to cargo_embargo. am: 8db550a9e9 am: 2dc01c2028 am: 1f9f8d21f8

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/threadpool/+/2828054

Change-Id: I9790b348527b387e0899eeba6eb00376ad3f5a6b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>