[FIX] website: hide backend navbar tour tips when entering edit mode

When entering edit mode, the navbar is hidden. The problem is that since
the merge of the website-in-backend feature at [1], it is only not shown
via an animation (height 0 + out of screen) but not `display: none`. The
tour system thus thinks it is still shown and keeps showing the related
tour tips.

E.g. with website_sale installed (and no demo data, to have the tours),
go on the shop page, there is a tooltip pointing at "+ New", enter edit
mode => the tooltip is still there and it even prevents to click on
"Discard" to leave the edit mode.

This commit fixes the issue by making the navbar `display: none` once
the closing animations are finished.

[1]: https://github.com/odoo/odoo/commit/31cc10b91dc7762e23b4bde9b945be0c4ce3fe3b



task-3082439

closes odoo/odoo#106629

Signed-off-by: Romain Derie (rde) <rde@odoo.com>