Mark individual step as failure
Mark individual step as failure

When investigating a problem it is usually more important to know
which individual step failed, than knowing the difference between
"tests failing" and "failed to build". Therefore use Jenkins "error"
command instead of marking the whole pipeline as "UNSTABLE".

Change-Id: Ia14be4e8c76062e142523f6d01417b0f6522036f

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration