Fix triton multicast

[lvboudre]

Current Problem

• Command line argument triton-multicast-num-threads if set to a number bigger than 1 would cause to join the multicast group N times and receiving the same traffic N times.
• Missing multicast-subscription-port, when joining the multicast group, we don't specify a multicast subscription port, and create a socket with a random port. So the multicast socket creates bind our procedure would receive nothing. Unless --src-bind-port was not properly set to a port that match on of the joined multicast group, the proxy would receive nothing.
• packet received by the multicast socket were never added to prometheus observation.

New

• Removed the triton-multicast-num-threads.
• Added CLI arguments triton-multicast-subscription-port.

Fixes

• When provided with CLI arguments to join a multicast group owned by triton, a dedicated socket is created and bind to 0.0.0.0:[triton-multicast-subscription-port].
• Refactor the code to remove duplicate code everywhere and used a unified approach to be aligned with jito's original code.