Merge "Clean up rust_test_host TEST_MAPPING after default update" am: 23d64a9487 am: 845a8d7c6c

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/proc-macro-hack/+/1589933

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I344e588df7b79ea7f1b4efaeae5b20cdfc52d5de