Temporarily exclude `JniCompilerTests` from the ART MTS definition. am: f53fa282cc am: 39091af211 am: 580e85a249 am: dabe6d2d7d

Original change: https://android-review.googlesource.com/c/platform/art/+/2218043

Change-Id: Id5f1199649bbf1b27897aaa45d7d04df2524492e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>