Introduce SidekiqEventReporter for the Watchdog

What does this MR do and why?

In !104987 (merged) we extracted the EvenReporter for the watchdog. This MR introduces SidekiqEventReporter which logs and collects additional metrics specific to Sidekiq.

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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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Related to: #384583 (closed)