Update Test924 to filter for messages related to test thread am: df4219a87b

Original change: https://android-review.googlesource.com/c/platform/art/+/2223919

Change-Id: I1aff7fcb383eabbc85f50e99046c294bb8d6a2d2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>