Revert "patman: test_util: Print test stdout/stderr within test summaries"

Revert "patman: test_util: Print test stdout/stderr within test summaries"

Unfortunately this adds a new feature to concurrencytest and it has not
made it upstream to the project[1].

Drop it for now so we can use the upstream module. Once it is applied we
can bring this functionality back.

[1] https://github.com/cgoldberg/concurrencytest

This reverts commit ebcaafcded40da8ae6cb4234c2ba9901c7bee644.

Signed-off-by: Simon Glass <sjg@chromium.org>