Dialog::setVisible doesn't do anything if the QML hasn't finished
setting initial properties (componentCompleted)
componentComplete() method used to duplicate the code that was in
Dialog::setVisible().
Dialog::setVisible was changed in
eab4aa9909a62cce9b32555ed28d142569fb467f. componentComplete was not.
Rather than copying the code, we can call the method directly.
BUG: 382340