AU test suite is stable -- remove the forgiving component.

BUG=chromium:223779
TEST=Pylint + unittests

Change-Id: Ib1ffaa909960ec0f47194532ed24785412549fdc
Reviewed-on: https://gerrit.chromium.org/gerrit/48177
Tested-by: Chris Sosa <sosa@chromium.org>
Reviewed-by: Ryan Cui <rcui@chromium.org>
Commit-Queue: Chris Sosa <sosa@chromium.org>
diff --git a/buildbot/cbuildbot_stages.py b/buildbot/cbuildbot_stages.py
index 112017b..a0e24ec 100644
--- a/buildbot/cbuildbot_stages.py
+++ b/buildbot/cbuildbot_stages.py
@@ -1595,7 +1595,7 @@
       return self.DealWithTimeout(exception)
 
 
-class AUTestStage(HWTestStage, ForgivingBuilderStage):
+class AUTestStage(HWTestStage):
   """Stage for au hw test suites that requires special pre-processing."""
 
   def _PerformStage(self):