tool_operate: retry on HTTP response codes 522 and 524

- Treat HTTP response codes 522 and 524 as a transient error since
  Cloudflare may use them instead of 504 to signal timeout.

For example here is a 522 error message from Cloudflare:

"The initial connection between Cloudflare's network and the origin web
server timed out. As a result, the web page can not be displayed."

Prior to this change the curl tool did not retry on HTTP response codes
522 and 524 when --retry was used.

Fixes https://github.com/curl/curl/discussions/16143
Closes https://github.com/curl/curl/pull/19011

src/tool_operate.c

@@ -412,6 +412,8 @@ static CURLcode retrycheck(struct OperationConfig *config,
       case 502: /* Bad Gateway */
       case 503: /* Service Unavailable */
       case 504: /* Gateway Timeout */
+      case 522: /* Connection Timed Out (Cloudflare) */
+      case 524: /* Proxy Read Timeout (Cloudflare) */
         retry = RETRY_HTTP;
         /*
          * At this point, we have already written data to the output