Feat: enable JH to override country list in trial

What does this MR do and why?

Before trials page gets refactored into Vue based parts, we have a MR for rendering JH country or region list in the trials page: !74037 (merged)

As for this MR, because the previous trials page has been replaced so that we need to implement a new way for JH to render JH version region list.

Describe in detail what your merge request does and why.

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