Geo Sites - Remove primary version duplication

What does this MR do and why?

Closes #4807 (closed)

Important: The term Node is being rebranded as Site in Geo. For this change the term Node <=> Site represents the same thing.

Important: In Geo there are Primary and Secondary sites. There can only ever be one Primary Site. The goal of the UI being touched here is to highlight a particular Site's version RED when it's GitLab version does not match the Primary Site's version.

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This change removes some technical debt of how we used to do this comparison years ago. In the past we didn't have a proper API to fetch the version information of each site. So we gathered it in Rails and sent it up with the data- into the Vue app. In the current state of things we already have all this information stored in the Vuex store and don't need this extra duplicated data. Removing it allows us to use the API as the SSoT.

Screenshots or screen recordings

There are no visual changes in the UI

No Mismatch	w/ Mismatch

How to set up and validate locally

1. Fetch and checkout this branch
2. Setup Geo (How to setup Geo)
3. Access your Primary GDK UI
4. Navigate to Geo Dashboard (/admin/geo/sites)
5. If you just set up Geo the Sites are likely on the same version and thus should not show the Red text for the Version
6. You can spoof the getter in the getters.js to return true to see the red text.

MR acceptance checklist

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