fix(discv5): change default discv5 port

[Rjected]

If discv5 is enabled while also running a lighthouse or other CL node that uses 9000 for its default port, then this will conflict and fail. Since op-reth nodes use discv5 and are often run on the same machine as a mainnet CL, it does not make sense to conflict by default. So this changes the default to 9200 which should prevent conflicts by default, and allow for many --instance nodes to run without conflicting

[onbjerg]

The test failure is due to ListenConfig::default being used, which defaults to port 9000. I've addressed it in #11060 which is stacked on top of this PR. I didn't do the work in this PR because I'm not sure if there's a better way to solve it:)

Also marked with M-changelog since we'd likely want to highlight that it changed if people have done port forwarding