Remove the possibility to set redis_slot in known_events

What does this MR do and why?

This MR is the next step in our effort to remove known_events folder. It removed redis_slot param from events configuration and uses the default slot instead.

Events are migrated during the renaming process.

Screenshots or screen recordings

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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 #280527 (closed)