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.
It makes more sense to call VXLAN ID as
1. the VXLAN Network Identifier (VNI) (or VXLAN Segment ID)
2. test-network: rename VXLAN Id to VNI
3. fuzzer: Add VXLAN VNI directive to fuzzer