Improving distributed tracing in Kibana

[mshustov]

List of tasks, based on the discussion in #97934:

• Implement Elasticsearch query tracing to a source in Kibana Implement Elasticsearch query tracing to a source in Kibana #101587
• Use APM RUM agent to pass Kibana execution context Use APM RUM agent to pass Kibana execution context #102615
• Use standard tracing headers for distributed tracing Implement Elasticsearch query tracing to a source in Kibana #101587

APM improvements:

• APM agents can be used without APM server add support for explicitly disabling sending to APM server apm-agent-nodejs#2101
• Set tracing headers for custom transactions Expose API to get/set tracing headers for custom transactions apm-agent-rum-js#468
• API for manual context management Provide API for manual Context management  apm-agent-rum-js#1040

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[trentm]

elastic-apm-node@3.17.0 supports disableSend:true for the "APM agents can be used without APM server" item now.

[pgayvallet]

All kibana items have been addressed, only ones remaining are from the APM repo, so I'll consider this done on our side and will close it.