1. Allow 'any' as an option to zeroconf-selective.py plugin so we can use
it in line_graph where we don't know ids yet.
2. Use modern helpers like line_graph and remove debugging statement.
3. Don't use listchannels(): it's true that it shows local channels as well,
but that's a quirk I'd like to remove.
4. Make flake8 happy.
5. Rename to be more specific now it's a more narrow test.
I manually tested that the test still failed with the fixes removed, too,
so it is still the same test!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
