make map_discv5_config_builder more ergonomic

[mattsse]

Describe the feature

reth/crates/net/network/src/config.rs

Line 428 in e78e726

pub fn map_discv5_config_builder(

this call has been the root cause for this regression and is a bit confusing #9058 (comment)

ideally this function is removed and combined with the setter:

reth/crates/optimism/node/src/node.rs

Line 291 in e78e726

builder = builder.discovery_v5(reth_discv5::Config::builder(rlpx_socket));

bonus points for an additional test

Additional context

No response

[yutianwu]

Do u mean we remove the map function and use setters when we initialize the builder like this?