Dashboard and visualizations tutorials revamp

# Idea

Tutorials are a great resource to learn a product capability.
Issues: our current tutorials about dashboards and visualizations (Lens) used to be the actual docs for these features, meaning that they're trying to cover everything on the same page, but at the same time they're outdated, and probably missing key foundational features added in the past couple of years. Another possible issue is that we should use more realistic data in these examples, that demonstrate Elastic's popular use cases.

To fix this, we should:

- Update existing (old) end-to-end basic tutorials. They’re outdated, not reflecting recent-ish features, using basic sample data.
- Review the scope of these tutorials: Are they really building knowledge about the fundamentals and best practices of these features? What should be added, what should be removed or rather described elsewhere? Does the structure still make sense?
- Create solution-specific tutorials with various types of data (Logs, Metrics, etc.) to showcase value users can get out of it