[FIX] website: restore parallax previews in edit mode

When the user changed the parallax option, it was only updated on save.
So, the user was not able to have a preview of what he chose.

Note: this commit is made in saas-12.3 but does not fully solve the
problem there... and unfortunately I don't know why. It fully solves
the problem in 13.0 though and this is more important.

closes odoo/odoo#39995

X-original-commit: 4b633949cd4fd1cae807b95d233879ac4adc01ce
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/static/src/js/content/snippets.animation.js

@@ -494,6 +494,7 @@ registry.slider = publicWidget.Widget.extend({
 
 registry.parallax = Animation.extend({
     selector: '.parallax',
+    disabledInEditableMode: false,
     effects: [{
         startEvents: 'scroll',
         update: '_onWindowScroll',