Added log to show which URL is blocked by CORS. (#26347)

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Co-authored-by: Mattermost Build <build@mattermost.com>

server/i18n/en.json

@@ -4552,7 +4552,7 @@
   },
   {
     "id": "api.web_socket.connect.upgrade.app_error",
-    "translation": "Failed to upgrade websocket connection."
+    "translation": "URL Blocked because of CORS. Url: {{.BlockedOrigin}}"
   },
   {
     "id": "api.web_socket_router.bad_action.app_error",