[FIX] web_editor: restore website header once page content is removed

The affixed header was not reappearing if page content was removed and
the page thus indirectly scrolled.

task-2446020

closes odoo/odoo#64999

X-original-commit: 4da6df09a4df195ad7c0caa7de7fbc7389339958
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -348,6 +348,11 @@ var SnippetEditor = Widget.extend({
         this.destroy();
         $parent.trigger('content_changed');
 
+        // TODO Page content changed, some elements may need to be adapted
+        // according to it. While waiting for a better way to handle that this
+        // window trigger will handle most cases.
+        $(window).trigger('resize');
+
         function isEmptyAndRemovable($el, editor) {
             editor = editor || $el.data('snippet-editor');
             return $el.children().length === 0 && $el.text().trim() === ''