Update TEST_MAPPING am: 66b21a5964

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/thiserror/+/2106893

Change-Id: Ib30b65911f3aeae00237399046154cf63e8e7817
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>