Bug: --p2p-udp-port is ignored for ENR/discovery_addresses advertised port

[MqllR]

Summary

When --p2p-udp-port is set to a value different from --p2p-port, the advertised UDP port in the ENR and in the /eth/v1/node/identity discovery_addresses field still shows the TCP port instead of the configured UDP port.

Steps to Reproduce

Start Teku with:

--p2p-port=9000
--p2p-udp-port=9001
--p2p-advertised-ip=<public-ip>

Query the identity endpoint:

GET /eth/v1/node/identity

Expected Behavior

discovery_addresses should contain /ip4/<public-ip>/udp/9001/... and the ENR should encode UDP port 9001.

Actual Behavior

discovery_addresses contains /ip4/<public-ip>/udp/9000/... and the ENR encodes UDP port 9000. The --p2p-udp-port=9001 value is silently ignored for the advertised port.

Root Cause

In P2PConfig.build() (networking/eth2/src/main/java/tech/pegasys/teku/networking/eth2/P2PConfig.java:361):

discoveryConfig.advertisedUdpPortDefault(OptionalInt.of(networkConfig.getAdvertisedPort())); // TCP port = 9000

This runs after P2POptions.configure() has called discoveryConfig.listenUdpPort(9001), and it fills in advertisedUdpPort with the TCP port (9000) because advertisedUdpPort is still empty at that point.

DiscoveryConfig.getAdvertisedUdpPort() is:

return advertisedUdpPort.orElse(listenUdpPort);

The intent was: fall back to listenUdpPort (9001) when no explicit --p2p-advertised-udp-port is set. But because advertisedUdpPortDefault runs after and fills in the value with 9000, the fallback to listenUdpPort is never reached.

Workaround

Add --p2p-advertised-udp-port=9001 explicitly alongside --p2p-udp-port=9001. Since this sets advertisedUdpPort to a non-empty value before P2PConfig.build() runs, the advertisedUdpPortDefault(9000) call becomes a no-op.

Fix Direction

P2PConfig.build() should only propagate the TCP advertised port as the UDP advertised default when --p2p-udp-port was not explicitly set. When a UDP listen port has been explicitly configured, it should take precedence over the TCP port for the UDP advertised default.