xhtml_style: remove timestamp from ckeditor URLs

This timestamp break officejs offline capabilities.

This reaplies 40f6c8fe ([erp5_xhtml_style] ckeditor: drop hardcoded
timestamp parameter in URL, 2017-10-16) on the updated CKEditor

This was done with:

    find product/ERP5/bootstrap/erp5_xhtml_style/SkinTemplateItem/portal_skins/erp5_ckeditor/ckeditor/ -type f  | xargs sed -i 's/"M6K9"/""/g'

M6K9 was the timestamp for this build, that we can see at the top of
ckeditor.js

product/ERP5/bootstrap/erp5_xhtml_style/SkinTemplateItem/portal_skins/erp5_ckeditor/ckeditor/ckeditor.js.js

@@ -2,7 +2,7 @@
 Copyright (c) 2003-2022, CKSource Holding sp. z o.o. All rights reserved.
 For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license/
 */
-(function(){if(window.CKEDITOR&&window.CKEDITOR.dom)return;window.CKEDITOR||(window.CKEDITOR=function(){var a=/(^|.*[\\\/])ckeditor\.js(?:\?.*|;.*)?$/i,d={timestamp:"M6K9",version:"4.19.1",revision:"445cf24ebd",rnd:Math.floor(900*Math.random())+100,_:{pending:[],basePathSrcPattern:a},status:"unloaded",basePath:function(){var b=window.CKEDITOR_BASEPATH||"";if(!b)for(var c=document.getElementsByTagName("script"),d=0;d<c.length;d++){var h=c[d].src.match(a);if(h){b=h[1];break}}-1==b.indexOf(":/")&&"//"!=b.slice(0,2)&&(b=0===b.indexOf("/")?location.href.match(/^.*?:\/\/[^\/]*/)[0]+
+(function(){if(window.CKEDITOR&&window.CKEDITOR.dom)return;window.CKEDITOR||(window.CKEDITOR=function(){var a=/(^|.*[\\\/])ckeditor\.js(?:\?.*|;.*)?$/i,d={timestamp:"",version:"4.19.1",revision:"445cf24ebd",rnd:Math.floor(900*Math.random())+100,_:{pending:[],basePathSrcPattern:a},status:"unloaded",basePath:function(){var b=window.CKEDITOR_BASEPATH||"";if(!b)for(var c=document.getElementsByTagName("script"),d=0;d<c.length;d++){var h=c[d].src.match(a);if(h){b=h[1];break}}-1==b.indexOf(":/")&&"//"!=b.slice(0,2)&&(b=0===b.indexOf("/")?location.href.match(/^.*?:\/\/[^\/]*/)[0]+
 b:location.href.match(/^[^\?]*\/(?:)/)[0]+b);if(!b)throw'The CKEditor installation path could not be automatically detected. Please set the global variable "CKEDITOR_BASEPATH" before creating editor instances.';return b}(),getUrl:function(a){-1==a.indexOf(":/")&&0!==a.indexOf("/")&&(a=this.basePath+a);return a=this.appendTimestamp(a)},appendTimestamp:function(a){if(!this.timestamp||"/"===a.charAt(a.length-1)||/[&?]t=/.test(a))return a;var b=0<=a.indexOf("?")?"\x26":"?";return a+b+"t\x3d"+this.timestamp},
 domReady:function(){function a(){try{document.addEventListener?(document.removeEventListener("DOMContentLoaded",a,!1),window.removeEventListener("load",a,!1),b()):document.attachEvent&&"complete"===document.readyState&&(document.detachEvent("onreadystatechange",a),window.detachEvent("onload",a),b())}catch(c){}}function b(){for(var a;a=c.shift();)a()}var c=[];return function(b){function e(){try{document.documentElement.doScroll("left")}catch(b){setTimeout(e,1);return}a()}c.push(b);"complete"===document.readyState&&
 setTimeout(a,1);if(1==c.length)if(document.addEventListener)document.addEventListener("DOMContentLoaded",a,!1),window.addEventListener("load",a,!1);else if(document.attachEvent){document.attachEvent("onreadystatechange",a);window.attachEvent("onload",a);b=!1;try{b=!window.frameElement}catch(d){}document.documentElement.doScroll&&b&&e()}}}()},b=window.CKEDITOR_GETURL;if(b){var c=d.getUrl;d.getUrl=function(a){return b.call(d,a)||c.call(d,a)}}return d}());