[IDEA] add flexibility on mapping between prometheus metrics and features

[sunya-ch]

What would you like to be added?

Currently we require code changes when we want to introduce a new prometheus metrics as a feature to the pipeline (as well as the feature group). We can make it more flexibility via some configuration file or config map.

Why is this needed?

To add more flexibility on introducing a new metric or using third party metric such as from DCGM exporter.