fix(api): Fix resetting sys var causing internal server error (#21604)

and sorts draft variables by their creation time, ensures a consist order.

api/core/workflow/nodes/http_request/executor.py

@@ -333,7 +333,7 @@ class Executor:
         try:
             response = getattr(ssrf_proxy, self.method.lower())(**request_args)
         except (ssrf_proxy.MaxRetriesExceededError, httpx.RequestError) as e:
-            raise HttpRequestNodeError(str(e))
+            raise HttpRequestNodeError(str(e)) from e
         # FIXME: fix type ignore, this maybe httpx type issue
         return response  # type: ignore