Improving the Logstash Logging subsystem (aka making it more precise)

A common pain point of logstash monitoring is processing its logs, they could become very big and verbose. I propose a set of actions that will help improve the overall logging system.
- Revisit logging with in logstash and their plugins to make it as accurate as possible, removing unnecessary log.
- Enable trace logs, they should be turn on by default and only available when debugging. This will help getting accurate logs only for parts under investigation.
- Let users decide to get only logs generated by a selected groups of components.

The intention of this issue is to discuss and generate ideas to have a clever logging infra, there related issues focused on implementation details.

Relates to #4548

The issue does not name files, tests, or an entry point. Review the logging subsystem and related issue #4548 first, then clarify the proposed logging scope, trace behavior, and component selection before implementation.

Written by the indexing model from the issue text.