Ensure the Thread integration test only run on CuttleFish devices

This is because the test case relies on **simulation** Thread radio, which is currently only available on CuttleFish.

Bug: 295843010
Test: atest android.net.thread.BorderRoutingTest

Change-Id: Icd29d91c9ec9912e27191e97fe7f58e9067c1d8c
2 files changed