[FIX] website: only show "welcome" message on empty homepage

Every new page was being considered an empty homepage with "Welcome to
your Homepage! Let's start designing." shown. Now only an empty homepage
shows that message.

closes odoo/odoo#30839

addons/website/static/src/js/menu/edit.js

@@ -48,7 +48,7 @@ var EditPageMenu = websiteNavbarData.WebsiteNavbarActionWidget.extend({
         var def = this._super.apply(this, arguments);
 
         // Check that the page is empty
-        var $wrap = this._targetForEdition().find('#wrap');
+        var $wrap = this._targetForEdition().filter('#wrapwrap.homepage').find('#wrap');
         this.$wrap = $wrap;
 
         if ($wrap.length && $wrap.html().trim() === '') {