Issue

Meta issue: elastic/beats#37086
To have journald GA, we should switch the Elastic Agent System Integration to use journald to read log data streams.
We will need to decide how to migrate existing log inputs to journald since:

• The auth datastream https://github.com/elastic/integrations/blob/main/packages/system/data_stream/auth/agent/stream/log.yml.hbs
• The syslog datastream https://github.com/elastic/integrations/blob/main/packages/system/data_stream/syslog/agent/stream/log.yml.hbs

In addition, we will need to define if we want to make this switch conditional on the Linux distribution specifically, or if a conditional being added only for Linux is enough.

Acceptance Criteria

• Auth datastream is available and use journald
• Syslog datastream is available and use journald