Fix CLN p2p port

[andrei-21]

LIGHTNINGD_PORT is not consumed by https://github.com/ElementsProject/lightning/blob/master/tools/docker-entrypoint.sh nor lightningd.
Before the fix:

$ nigiri lnd connect `nigiri cln getinfo | jq -r .id`@cln:9935
[lncli] rpc error: code = Unknown desc = dial tcp 172.24.0.4:9935: connect: connection refused
exit status 1

After the fix:

$ nigiri lnd connect `nigiri cln getinfo | jq -r .id`@cln:9935
{

}

[andrei-21]

@tiero can you review it please? Do you need any help?

[tiero]

Done!

[andrei-21]

Thanks!