[VOL-4521] - Make disble/enable ONU and PON port tests non-critical

Change-Id: I832d98151ac675a490dd823f48f19aef19982376
diff --git a/tests/dt-workflow/Voltha_DT_FailureScenarios.robot b/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
index 6c34f6e..08588db 100755
--- a/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
+++ b/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
@@ -789,6 +789,9 @@
         Wait Until Keyword Succeeds    ${timeout}    5s
         ...    Validate Device    ENABLED    ACTIVE
         ...    REACHABLE    ${src['onu']}    onu=True    onu_reason=omci-flows-pushed
+        # Workaround for issue seen in VOL-4489. Keep this workaround until VOL-4489 is fixed.
+        Run Keyword If    ${has_dataplane}    Reboot XGSPON ONU    ${src['olt']}    ${src['onu']}    omci-flows-pushed
+        # Workaround ends here for issue seen in VOL-4489.
         Run Keyword If    ${has_dataplane}    Run Keyword And Continue On Failure
         ...    Wait Until Keyword Succeeds    ${timeout}    2s
         ...    Check Ping    True    ${dst['dp_iface_ip_qinq']}    ${src['dp_iface_name']}