Migrate to cargo_embargo. am: 04b026a7b9 am: ec11cea8dc am: 68067c28ff

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tracing-core/+/2832579

Change-Id: Ie4ddb3787fd1262f711799cdc6c92706211e240f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>