[Azure docs] Add a new use case on how to collect any metric using the Azure Monitor

### Description

Now that the existing Azure tutorials have been refactored under the new Azure monitoring section, we can add a new use case on how to collect any metric using the Azure Monitor.

Relates to https://github.com/elastic/observability-docs/issues/3742

### Resources

- Some draft content is available in https://github.com/zmoog/public-notes/issues/69
- Original GH issue: https://github.com/elastic/integrations/issues/8849

### Which documentation set does this change impact?

Stateful and Serverless

### Feature differences

None

### What release is this request related to?

N/A

### Collaboration model

The documentation team

### Point of contact.

@maurizio