feat(rag): parallelize MinIO payload fetches for citations and VLM

[smasurekar]

Description

feat(rag): parallelize MinIO payload fetches for citations and VLM

Mirror PR: #414

Checklist

• I am familiar with the Contributing Guidelines.
• All commits are signed-off (git commit -s) and GPG signed (git commit -S).
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• If adjusting docker-compose.yaml environment variables have you ensured those are mimicked in the Helm values.yaml file.