Replace access to container in internal API

What does this MR do?

In e8ca2229 we added container as an attribute inside API::Helpers::InternalHelpers. Nevertheless, it should work like the repo_type and project methods, parsing the repository path and populating the other variables.

In this MR we also rename the method set_project to parse_repo_path because that aligns more with what the method does and it's the same name we use in the HTTP controllers.

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