Correct reraising of exception

when an exception was caught and rethrown, it should call 'raise'
without any arguments.

Change-Id: Ifedddb352910f8c499c0ca36c2377567c59c1de5
diff --git a/tempest/stress/actions/unit_test.py b/tempest/stress/actions/unit_test.py
index 3b27885..e016c61 100644
--- a/tempest/stress/actions/unit_test.py
+++ b/tempest/stress/actions/unit_test.py
@@ -80,8 +80,6 @@
 
             try:
                 self.run_core()
-            except Exception as e:
-                raise e
             finally:
                 if (CONF.stress.leave_dirty_stack is False
                     and self.class_setup_per == SetUpClassRunTime.action):