move proxy intercept errors to error-pages.conf

sites/client.conf

@@ -8,6 +8,7 @@ server {
         include /etc/nginx/snippets/proxy-params.conf;
     }
     location /api/ {
+		proxy_intercept_errors off;
         proxy_pass http://proxmoxaas.dmz:80;
         include /etc/nginx/snippets/proxy-params.conf;
     }