Ui text: fix deletion of the swallowed text object

Ui text: fix deletion of the swallowed text object

The Efl.Canvas.Text object loses its parent due to a specific behavior
of Edje when swallowing objects.
The mentioned object then loses sync with the Ui.Text object, thus not
getting deleted upon destruction - that's actually because Edje
reparents to the canvas upon its own deletion.
Adding this fix until we figure out if there is a better alternative.