Space-to-Space requests to *.hf.space return 503 from awselb since Jul 8

Since July 8, 2026, HTTP requests originating from inside a Hugging Face Space container to any *.hf.space host are returning HTTP 503 errors. The AWS load balancer (awselb/2.0) responds directly with an empty data body, preventing the request from reaching the target Space.

• Verified across multiple user Spaces and Gradio Spaces.
• Occurs regardless of whether a valid PRO token is provided.
• Reproduced from different container egress IPs with identical DNS resolution.
• External requests to the same URLs continue to return 200 OK.

This regression breaks the documented pattern for calling a ZeroGPU Space from another Space via gradio_client.