Partners site hydration

[seanmalbert]

• General
• Backend
• Public
• Partners

Background / Issue

The Partners portal renders the same global overrides for all users regardless of jurisdiction
(Partners is jurisdiction-independent), sourced from the DB rather than the bundled override file.

Technical Context

• TDD: §5.5.
• Load the global (null, language, partners) overrides into the Partners polyglot via the
  jurisdiction-independent read (GET /translations?site=partners&language=), layered over the
  bundled base. No per-jurisdiction resolution on the Partners side.
• Depends on: Translation read/merge service and public read endpoints #6509

Acceptance Criteria

• The Partners portal applies the global Partners overrides for all users, layered over the bundled
  base.
• No per-jurisdiction resolution is attempted on the Partners side.

QA Notes

Partners portal. Confirm the portal reflects the global Partners overrides and that users in
different jurisdictions see the same overrides.