gio-tool-open: Use g_app_info_launch_default_for_uri_async()
gio-tool-open: Use g_app_info_launch_default_for_uri_async()

The recent changes of the g_app_info_launch_default_for_uri_async()
function ensures that the callback is not called before DBus-activated
applications start. Let's use g_app_info_launch_default_for_uri_async()
and remove the workarounds for DBus-activated applications.

Closes: https://gitlab.gnome.org/GNOME/glib/issues/1249

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib