packetbeat: prevent metric collection ID collision and improve sniffer performance

[efd6]

The metric ID collision needs to be handled better. We have had an internal discussion and the approach that we will take is a 3-step plan:

• add index to metric ids (this will fix a panic issue and is quick) packetbeat/sniffer,packetbeat/protos/{tcp,udp}: prevent identical interfaces from colliding in metric namespace #36575;
• deduplicate interfaces (this is a little longer term and will improve performance) packetbeat/beater: deduplicate interface configs #36576;
• de-hoist protos.NewProtocols() and protocols.Init() into setupSniffer to make each sniffer child have its own proto list (this is more invasive but will improve UX and performance).

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)