tests/unit: Remove debug statements in test-nested-aio-poll.c

tests/unit: Remove debug statements in test-nested-aio-poll.c

We have been running this test for almost a year; it
is safe to remove its debug statements, which clutter
CI jobs output:

  ▶  88/100 /nested-aio-poll                      OK
  io_read 0x16bb26158
  io_poll_true 0x16bb26158
  > io_poll_ready
  io_read 0x16bb26164
  < io_poll_ready
  io_poll_true 0x16bb26158
  io_poll_false 0x16bb26164
  > io_poll_ready
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_poll_false 0x16bb26164
  io_read 0x16bb26164
  < io_poll_ready
  88/100 qemu:unit / test-nested-aio-poll        OK

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240422112246.83812-1-philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>