Stop nova conductor properly (singleconductor mode)

stop_nova_conductor dropped the ball when the CELLSV2_SETUP mode is
set to "singleconductor". We should cleanup the older style "n-cond"
in this case.

Change-Id: I9ffd6d09df6f390a842b8a374097f144564d2db4

lib/nova

@@ -988,6 +988,11 @@ function stop_nova_rest {
 }
 
 function stop_nova_conductor {
+    if [[ "${CELLSV2_SETUP}" == "singleconductor" ]]; then
+        stop_process n-cond
+        return
+    fi
+
     enable_nova_fleet
     for srv in n-super-cond $(seq -f n-cond-cell%0.f 1 $NOVA_NUM_CELLS); do
         if is_service_enabled $srv; then