Clean up rust_test_host TEST_MAPPING after default update am: 84fc652c2d am: 714b933e7e

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/unicode-width/+/1584386

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Icb45d16a24d61be508a3155ff83be2bdf5040452