[VOL-4041] Migration to single ONOS SSH connection

Change-Id: I91f5f3c96585097486bc862118d8753bf4b30cba
diff --git a/tests/software-upgrades/ONU_Upgrade.robot b/tests/software-upgrades/ONU_Upgrade.robot
index 40b4e1d..0230bb1 100755
--- a/tests/software-upgrades/ONU_Upgrade.robot
+++ b/tests/software-upgrades/ONU_Upgrade.robot
@@ -154,3 +154,4 @@
 Teardown Suite
     [Documentation]    Tear down steps for the suite
     Run Keyword If    ${has_dataplane}    Clean Up Linux
+    Close All ONOS SSH Connections