[2.4.8-beta2] Downgrade TinyMCE dependency from version 7 to version 6.8.5

Author: jayrangnani-gl

lib/web/mage/adminhtml/wysiwyg/tiny_mce/tinymceAdapter.js

@@ -674,7 +674,6 @@ define([
                     decodedDirectiveString;
                 // process tag attributes string
                 // eslint-disable-next-line no-useless-escape
-
                 attributesString = attributesString.gsub(/([a-z0-9\-\_]+)="(.*?)(\{\{.+?\}\})(.*?)"/i, function (m) {
                     decodedDirectiveString = encodeURIComponent(Base64.mageEncode(m[3].replace(/"/g, '"') + m[4]));