Those are all consumed by our parser, so they all support comments.
I was considering whether they should have a license header at all,
but in the end I decided to add it because those files are often created
by copying parts of real unit files. And if the real ones have a license,
then those might as well. It's easier to add it than to make an exception.
The test currently doesn't actually test configure-without-carrier since
it does have carrier for the entire test. It now forces carrier down
before starting the network portion of the test. Also, it tests to verify
the configuration is retained across future carrier losses/gains.