refactor: move ratelimiter configuration to handler package

What does this MR do?

See #670.

The idea is to simplify the main package. Since I'm currently working on ratelimiter, I started with it. We can continue working on other parts of pipeline later.

Based on !638 (diffs), so marked as draft until it's merged.

It's also part of #630 (closed)

TODO

• I added the Changelog trailer (e.g. Changelog: feature) to the commits that need to be included in the changelog
• I added unit tests or they are not required
• I added acceptance tests or they are not required
• I added documentation (or it's not required)
• I followed code review guidelines
• I followed Go Style guidelines