node_type->has_title removed in favor of entity form displays

Now that it is possible to configure the behavior of the node title widget using Entity form displays, the special flag to hide the title form element for nodes is no longer needed.

To hide the title for a certain node type, use the "Manage form display" UI or hide it with a snippet like the following:

$form_display = entity_get_form_display('node', 'article', 'default') {
$form_display->removeComponent('title');
$form_display->save();