Update TEST_MAPPING am: 3918c6ea30 am: cd42fa54b2 am: 1403ba9776

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/synstructure/+/2411794

Change-Id: I0b564394f40ccbbb498eb095fd16349fd6fb09fe
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>