Clean up rust_test_host TEST_MAPPING after default update am: 0eed533e99 am: 8104f5e7e5 am: 37bd55757f

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rustc-hash/+/1585228

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Icd4bde5794eb7551b6aca6541faaef1baa691f7a