Simplify ApplicationRateLimiter

Pavel Shutsinrequested to merge
347550-gitlab-applicationratelimiter-declared-as-class-but-used-as-a-module into master

What does this MR do and why?

Removes unused methods as part of technical debt cleanup.

MR acceptance checklist

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

Related to #347550 (closed)

Merge request reports