Refactor Geo tests folder structure

What does this MR do and why?

Describe in detail what your merge request does and why.

Replaces geo stage folder with systems to reflect the current state of things specified in https://about.gitlab.com/handbook/product/categories/#systems-stage.

Plus general refactoring to resolve any RuboCop offences in the moved files.

Part of https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/1284

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