Fix braino in knownfailures.json. am: 260d3997a1 am: 8b186d3804 am: f596d2010b

Original change: https://android-review.googlesource.com/c/platform/art/+/2460188

Change-Id: Ida1793b987e22d1391e29b454dd5267a621cf33b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>