virt-aa-helper-test: only fails go to stdout by default
    
    By Default (without -d) the tests will only print Failures.
    So a log should follow general "no message is a good message" style.
    
    But the testfw checks always emit the skip info to stdout. Instead
    they should use the redirection that is controlled by -d.
    
    This avoids mesages like the following to clutter the log:
      Skipping FW AAVMF32 test. Could not find /usr/share/AAVMF/AAVMF32_CODE.fd
    
    Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>