This is for integration with Elastic Agent, part of #4004

The new indexing strategy is defined here.

TL;DR

Index names will have 3 variable "chunks": type and service name, that come from ingested data; and namespace, that comes from Elastic Agent.
service name and namespace are user-defined, while type is well known in advance and can be logs, metrics, or traces.
We need to route the right events to the right indices based on those variables.

Requires

For service name:
elastic/package-spec#64

For traces type:
elastic/package-spec#68
elastic/kibana#81451
elastic/elasticsearch#64047