travis/gitlab/azure: Drop repeated buildman call with test.py

It does not seem to be necessary to run buildman again to show errors,
since any errors can be shown by the first invocation and there is only
a single board being built. Update this to simplify the code, using the
-e flag to make sure errors are shown.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>