Clean up rust_test_host TEST_MAPPING after default update am: 3d62e3b986

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/tinyvec_macros/+/1584444

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I41be181846135f9a1870b150405cb659b5fab4e7