tests/qtest/cdrom-test: replace HMP "info block" with QMP query-block

The test_cdrom_param() function uses qtest_hmp() to run "info block",
which depends on the human-monitor-command QMP endpoint. Replace it
with the QMP query-block command so the test works when HMP is
disabled (-Dhmp=disabled).

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20260828-qemu-no-hmp-v5-15-9227de146347@redhat.com>