build-tools/test-recursively: Tweak the output to be less verbose
build-tools/test-recursively: Tweak the output to be less verbose

Unless we run into an error, try to fit the output to one per directory. Also
make the errors stand out more visibly.

This should make it much easier to spot errors in a larger build log.

Signed-off-by: Gergely Nagy <6780fac3b38619ac20422286e4110a70dbba2203@madhouse-project.org>

keyboardio/Arduino