refactor: remove ssrf_filter dependency

[gildesmarais]

Summary

• remove the custom ssrf_filter request strategy and its boot wiring
• switch backend defaults and strategy metadata to supported request-service strategies
• update Ruby and smoke specs to match the new strategy baseline

Verification

• docker compose -f .devcontainer/docker-compose.yml run --rm app make setup
• docker compose -f .devcontainer/docker-compose.yml run --rm app make ready