refactor: make internal/lru and internal/ratelimiter metrics optional

What does this MR do?

• make internal/lru metrics optional
• Convert metrics in ratelimiter.New to functional options as well
• cleanup tests by removing mock metrics

Closes #647 (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