Add test config to bluetoothtbd_test

This change allows TradeFederation to run the test directly.
Refer to b/35882476 for design and discussion of this change.

Bug: 35882476
Test: local test
tradefed.sh run template/local --template:map test=bluetoothtbd_test

Change-Id: I6a243fc0245e4c3aa0fc51f3ded40c63492e31e8