[ONOS-6901] Fix how the systemTest does not return any result when it forced to quit the test

Change-Id: If93c48d46e8dc2494046b42de21f732775d7f520
diff --git a/TestON/tests/PLAT/PLATdockertest/PLATdockertest.py b/TestON/tests/PLAT/PLATdockertest/PLATdockertest.py
index f61c305..a64ad3a 100755
--- a/TestON/tests/PLAT/PLATdockertest/PLATdockertest.py
+++ b/TestON/tests/PLAT/PLATdockertest/PLATdockertest.py
@@ -106,12 +106,10 @@
                                     onfail = "docker is not running")
         if stepResult == main.FALSE:
             main.log.warn("docker is not running - exiting test")
-            main.exit()
-            main.cleanup()
+            main.cleanAndExit()
         if imageTagCounter > len( imageTagList ):
             main.log.info("All images have been tested")
-            main.exit()
-            main.cleanup()
+            main.cleanAndExit()
 
     def CASE5(self, main):
         """