Add trace correlation to agent logs #2495
Description
Is your feature request related to a problem?
When agent logs in ECS format, we can utilize log correlation to our logs as well.
Describe the solution you'd like
We can enhance our co.elastic.apm.agent.logging.Log4j2LoggerBridge to add to slf4j MDC before any logging event and removing after if the log format is JSON.
Describe alternatives you've considered
Another option is to utilize log4j extension capabilities - org.apache.logging.log4j.core.util.ContextDataProvider or org.apache.logging.log4j.core.ContextDataInjector
Additional context
Followup on #2428