Delete sidekiq worker classes

What does this MR do and why?

Since !121626 (merged) is merged, now we delete sidekiq worker classes and add migration to remove jobs from the queue.

Address #397147 (closed)

Screenshots or screen recordings

NA

How to set up and validate locally

Since this is done post-removal of worker logic, there is nothing to verify here. Everything else should just work here.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

Related to #397147 (closed)