tests/qtest/qom-test: Do not print tested properties by default

tests/qtest/qom-test: Do not print tested properties by default

We're still running into the problem that some logs are cut in the
gitlab-CI since they got too big. The biggest part of the log is
still the output of the qom-test. Let's stop printing the properties
by default to get to a saner size here. The full output can still
be enabled by setting V=2 (or higher) in the environment.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20221215153036.422362-1-thuth@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>