minor improvements
Remove unused logger
Remove resource guard rule.

Special path "merged-resources" is not used since Wicket 6.0.0
WICKET-5375 Improve ConcatBundleResource error handling when a resource is missing
WICKET-5369 Can't set a cookie using CookieUtils during an ajax request due to java.lang.ClassCastException: org.apache.wicket.ajax.AbstractAjaxResponse$AjaxResponse cannot be cast to org.apache.wicket.request.http.WebResponse