Enable VNC console in tempest.conf

If the NoVNC service is enabled, enable vnc_console in tempest.conf.
This will allow tempest tests that interact with VNC to be executed.

Change-Id: Idb38a3b11e2f61f23adf1ec23c04ddccd72e7539
Depends-On: I09aed8de28f1ba2637382e870134ced38808df29
diff --git a/lib/tempest b/lib/tempest
index 3312522..9f89dbe 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -377,6 +377,10 @@
         fi
     fi
 
+    if is_service_enabled n-novnc; then
+        iniset $TEMPEST_CONFIG compute-feature-enabled vnc_console True
+    fi
+
     # Network
     iniset $TEMPEST_CONFIG network api_version 2.0
     iniset $TEMPEST_CONFIG network project_networks_reachable false