Clean up rust_test_host TEST_MAPPING after default update am: 1397d1fa26

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/ring/+/1582783

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I3ce55b78feda80334b0f048588b5fb64d1dbfdcb