Re enable port conflict related Windows tests

[oxarbitrage]

In #8551 we disabled some Windows tests that were failing with port conflicts to often.

Possible design:

Use OS assigned ports whenever binding a TcpListener and get the socket address directly from the TcpListener:

• Return the listen address from open_listener() in the peer set init() function and use it instead of the random known port
• Use the address() method on Server in zebra-rpc (server_instance.address())
• Bind a TcpListener in zebra-grpc, return the address (maybe via a oneshot channel? Or by spawning a tokio task and returning the value from the init function) and replace the call to Router.serve() with serve_with_incoming()
• Use port 0 for the RPC listen addr and read the RPC socket address from the Zebra's logs when spawning TestChilds instead of using the config value