Switch BetaBadge monolith component for GlExperimentBadge

What does this MR do and why?

This MR addresses issue: #463490 . The main change is replacing the custom badge component from the monolith with the GlExperimentBadge gitlab-ui component to use as a single source of truth. I also added a test to verify the existence of the beta badge.

Note: The GlExperimentBadge does not have any hover capabilities at the moment. The old beta badge would still show you the text even if the mouse just hovers over it. Let me know if this is a blocking change or if there should be any consideration for adding hover support to GlExperimentBadge.

I also had to overwrite the margins as natively the GlExperimentBadge has a margin that misaligns with the original design.

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