After 3a798039d6, the emoji in the chat box is not
properly position. This is because of the change in logic in the application
of the calculated position to take into account the tour pointer.
This commit restores the logic of reposition and then made the tour pointer to use
the onPositioned option to properly reposition its element.
closes odoo/odoo#115479
Signed-off-by: Bruno Boi (boi) <boi@odoo.com>