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: NChristian Ehrhardt <christian.ehrhardt@canonical.com>