Qemu: Ensure ART_SSH_CMD is defined when running tests am: 5b2f97b131

Original change: https://android-review.googlesource.com/c/platform/art/+/2977711

Change-Id: I557e66ffe9c20f8ff58cf6b9b6737df61a920166
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>