Check inference health

Endpoint to check the health status of various components.

This function verifies the health of the service discovery module and the engine stats scraper. If either component is down, it returns a 503 response with the appropriate status message. If both components are healthy, it returns a 200 OK response.

Returns: Response: A JSONResponse with status code 503 if a component is down, or a plain Response with status code 200 if all components are healthy.