Deprecate `apm_system` user

[bmorelli25]

Summary

Deprecate the `apm_system user role and describe the required privileges instead.

Where?

• https://www.elastic.co/guide/en/apm/server/current/privileges-to-publish-monitoring.html#privileges-to-publish-monitoring-internal
• https://www.elastic.co/guide/en/apm/server/current/monitoring-internal-collection.html

Notes

• Default approach in 7.16 is Agent + Metricbeat. apm_system will not be required.
• Cloud standalone mode will be default in 7.16, but metrics collection via Metricbeat is enabled, so no need for apm_system.
• New APM integration docs do not need to mention internal monitoring -- only the deprecated APM Server reference needs to be updated.

Related

Related to elastic/apm-server#5987.

[bytebilly]

From an Elasticsearch perspective, we haven't implemented the deprecation yet. I suggest that we align to mark the user/role as "deprecated" in both documentation and code at the same time.

elastic/elasticsearch#80752

[bmorelli25]

I suggest that we align to mark the user/role as "deprecated" in both documentation and code at the same time.

Thanks! I've removed the timeline from this issue and will wait to update our docs until this is removed from ES.