Resolve underlying http closing/retry issue

[jaronoff97]

edge/src/proxy/server.zig

Line 569 in 727cdbb

std.mem.eql(u8, err_name, "HttpConnectionClosing") or

2026-01-08T19:06:02.364Z [ERROR] upstream.connection.error err="HttpConnectionClosing" phase="receive_head" underlying_err=null
2026-01-08T19:06:02.365Z [ERROR] upstream.connection.error err="HttpConnectionClosing" phase="receive_head" underlying_err=null
2026-01-08T19:08:32.367Z [ERROR] upstream.connection.error err="HttpConnectionClosing" phase="receive_head" underlying_err=null
2026-01-08T19:08:32.367Z [WARN] upstream.retry attempt=1 max_retries=10 err="HttpConnectionClosing"
2026-01-08T19:08:32.367Z [WARN] upstream.retry attempt=2 max_retries=10 err="HttpConnectionClosing"

After around 10-15 minutes we get these intermittent failures that are mitigated through some retries, but ideally we don't retry at all. I think this is just because of some TTLs and tied to this issue w/ the zig std library. We could probably find a better way of doing this.