ui/dbus: implement display cleanup

Add dbus_cleanup() to unparent the D-Bus display object, ensuring
proper teardown before user_creatable_cleanup() runs.

Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20260623-b4-ui-v4-21-4656aec3398d@redhat.com>

ui/dbus.c

@@ -615,10 +615,23 @@ static const TypeInfo dbus_display_info = {
     }
 };
 
+static void
+dbus_cleanup(void)
+{
+    Object *o;
+
+    o = object_resolve_path_component(object_get_objects_root(),
+                                      "dbus-display");
+    if (o) {
+        object_unparent(o);
+    }
+}
+
 static QemuDisplay qemu_display_dbus = {
     .type       = DISPLAY_TYPE_DBUS,
     .early_init = early_dbus_init,
     .init       = dbus_init,
+    .cleanup    = dbus_cleanup,
     .vc         = "vc",
 };