Improve routing cop

What does this MR do?

Improves routing cope by ignoring root routes like get '/' or post '/'. So we don't need to disable those lines with # rubocop:disable as false-positives

For #230703

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content