pidfd: kill the no longer needed do_notify_pidfd() in de_thread()

Now that __change_pid() does wake_up_all(&pid->wait_pidfd) we can kill
do_notify_pidfd(leader) in de_thread(), it calls release_task(leader)
right after that and this implies detach_pid(leader, PIDTYPE_PID).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240202131248.GA26022@redhat.com


Signed-off-by: Christian Brauner <brauner@kernel.org>