Remove automatic metrics calculation based on known_events

What does this MR do and why?

The legacy way of adding Redis metrics using known_events can be removed now since all the metrics been migrated to instrumentation classes.

All the metrics are now added automatically and covered by spec

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #378642 (closed)