RMST-472 - Make remote-settings v2 routes the default going forward

[alexcottner]

Remote-Settings v2 routes default

This PR removes the v1 remote-settings servers and makes v2 servers default going forward.

Pull Request checklist

• Breaking changes: This PR follows our breaking change policy
  • This PR follows the breaking change policy:
    • Phab patch D313608 should land before this to prevent android breaks
    • iOS PR 34782 should land before this to prevent iOS breaks
• Quality: This PR builds and tests run cleanly
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• Tests: This PR includes thorough tests or an explanation of why it does not
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