[VOL-3147] adding timeout after volt-remove-sub and onu-delete calls

Change-Id: I293d6aad3b1d4984a58eda707495b88cfea16a45
diff --git a/tests/dt-workflow/Voltha_DT_FailureScenarios.robot b/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
index 7c779eb..42933fa 100644
--- a/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
+++ b/tests/dt-workflow/Voltha_DT_FailureScenarios.robot
@@ -88,6 +88,7 @@
         # Remove Subscriber Access (To replicate DT workflow)
         Wait Until Keyword Succeeds    ${timeout}    2s    Execute ONOS CLI Command    ${ONOS_SSH_IP}
         ...    ${ONOS_SSH_PORT}    volt-remove-subscriber-access ${of_id} ${onu_port}
+        Sleep    10s
         # Delete ONU Device (To replicate DT workflow)
         Delete Device    ${onu_device_id}
         Sleep    5s