monaco: increase debounce timeout for pylint checks

on very large python files (>1000 lines) sometimes they queue up and we
have to wait for all requests that were queued by zope.

XXX maybe this does not happen when accessing through haproxy/apache, I
am observing this when hitting zope directly

bt5/erp5_monaco_editor/SkinTemplateItem/portal_skins/erp5_monaco_editor/monaco_editor_support.zpt

@@ -247,7 +247,7 @@ $script.onload = function() {
       function makeTimeoutFunction(ac){
         return () => checkPythonSourceCode(ac)
       }
-      timeout = setTimeout(makeTimeoutFunction(controller), 300);
+      timeout = setTimeout(makeTimeoutFunction(controller), 3000);
     }
   });