Extracted auxiliary methods from storage.rake into specific RakeHelper

What does this MR do?

Refactor storage.rake, extracting rake defined method to specific RakeHelper module.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

See discussion in https://gitlab.com/gitlab-org/gitlab-ce/issues/46370

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• End-to-end tests pass (package-and-qa manual pipeline job)