chore: remove Vespa and consolidate the document index interface (#15336)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/pr-python-tests.yml

@@ -53,7 +53,7 @@ jobs:
       REDIS_CLOUD_PYTEST_PASSWORD: ${{ secrets.REDIS_CLOUD_PYTEST_PASSWORD }}
       DISABLE_TELEMETRY: "true"
       # Unit tests run without a live backend; EE code paths that depend on
-      # Redis/Vespa/etc are not available, so disable enforcement here.
+      # Redis/OpenSearch/etc are not available, so disable enforcement here.
       LICENSE_ENFORCEMENT_ENABLED: "false"
 
     steps: