Migrate to cargo_embargo. am: 73154adc13

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

Change-Id: I7e78a0f5b4df1b0fec72eb00e7458d0d0acda2aa
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>