Migrate to cargo_embargo. am: 73154adc13 am: 04a4b2360a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/once_cell/+/2828068

Change-Id: I56a94a5d16e2802ed7f3a0af51147078ab3097c8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>