config: disable overpass proxy probe by default

vendor/clouds3d.js

@@ -3199,6 +3199,7 @@ function opProbeProxy() {
     if (_opProxyChecked) return;
     _opProxyChecked = true;
     if (location.protocol === 'file:') return;
+    if (!(window.CONFIG && window.CONFIG.overpass && window.CONFIG.overpass.useProxy)) return;
     fetch(OP_PROXY[0], {
         method: 'POST',
         headers: { 'Content-Type': 'application/x-www-form-urlencoded' },