Clean up rust_test_host TEST_MAPPING after default update am: b8bba2380d am: f7add38751

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/bitflags/+/1582230

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I8429df0a9d074d975f101e8ea20c8f7dc5830dab