tests/avocado: use the new snapshots for testing

The tuxboot images now have a stable snapshot URL so we can enable the
checksums and remove the avocado warnings. We will have to update as
old snapshots retire but that won't be too frequent.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230424092249.58552-3-alex.bennee@linaro.org>
1 file changed