Migrate to cargo_embargo. am: 57a5148ddd

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/indexmap/+/2832458

Change-Id: Icb15e50f8c295107d993e18c9ea00c19ec49beff
Signed-off-by: Automerger Merge Worker <[email protected]>