Clean up rust_test_host TEST_MAPPING after default update am: b6bfc7ac1c

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/parking_lot_core/+/1582330

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I39f0ea2c3ab5507b06df9133273ee9edbcf3f749