Replace httpbin.org health check with Cloudflare trace endpoint

[floydous]

httpbin.org frequently returns 503 or times out, causing working proxies to be marked as failed.
Could the health check use:
https://1.1.1.1/cdn-cgi/trace instead?

It returns a lightweight plain-text response containing the detected IP and connection details. It is also served through Cloudflare’s global anycast network, so requests are routed to a nearby Cloudflare location rather than depending on one regional server.

This should make proxy health checks faster and less prone to false failures.