[💡 FEATURE REQUEST]: Add support for custom prefixes in metrics plugin

[Buravenkov]

Plugin

Metrics

I have an idea!

Problem

Currently, built-in metrics such as rr_jobs_total_workers and rr_jobs_worker_memory_bytes, etc. cannot be customized. This makes it difficult to distinguish metrics when multiple microservices are using RoadRunner.

Proposed Solution

Add the ability to:

• Set a custom prefix for built-in metrics.
• Or add the ability to specify custom labels for internal metrics (e.g., service=my-microservice).

This would help in multi-service environments and make monitoring easier.