intel/tools: Use subprocess.Popen to read output directly from a pipe
Instead of using tempfiles to communicate between child & parent process. The latter sometimes resulted in hitting the meson timeout if there was high filesystem pressure. Fixes: ccaa5b03 "intel/tools: rewrite run-test.sh in python" Reviewed-by:Dylan Baker <dylan.c.baker@intel.com> Part-of: <mesa/mesa!9528>