Temporarily exclude `JniCompilerTests` from the ART MTS definition. am: f53fa282cc

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

Change-Id: I0ab01bdd3a136064beb570ce88e8557208837a29
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>