Add bug component for Rust (688011) to OWNERS of tokio* am: b70cc2907a am: 3575c34ee9

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tokio-stream/+/2689067

Change-Id: I3e0bb3de71a55ccbc7ba0fa154bfa9e2c9112232
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>