In owl 2, the t-on directive is no longer supported on components. The way to handle events on components is to give them a callback as a prop. This already works in owl 1, so this commit prepares the code for an easier migration in the future by removing the "dropdown-item-selected" event and converting the code that was using it to use the new paradigm. closes odoo/odoo#80684 Related: odoo/enterprise#22722 Signed-off-by: Géry Debongnie <ged@odoo.com>