Clean up rust_test_host TEST_MAPPING after default update am: a6e08a0d70 am: 071c19db01

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/url/+/1582765

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I5067f280251ef8afaee673a5e3212513b1dad32d