lib/neutron: Create initial topology only on controller node

To avoid it being created multiple times for multinode setup.

Note: This reverts "Enable neutron to work in a multi node setup"
(commit 88f8558d874072536e7660a233f24207a7089651) partly and fixes
the issue differently.
The configuration in question uses the new lib/neutron. (not neutron-legacy)
In that case, calling create_neutron_initial_network from stack.sh directly
is a wrong way, as create_neutron_initial_network is sourced by
neutron-legacy.  The new neutron code should not rely on the legacy one.

Closes-Bug: #1613069
Change-Id: I868afeb065d80d8ccd57630b90658e330ab94251
diff --git a/lib/neutron b/lib/neutron
index 53fc5fc..9923721 100644
--- a/lib/neutron
+++ b/lib/neutron
@@ -431,15 +431,17 @@
     if is_service_enabled neutron-l3; then
         run_process neutron-l3 "$NEUTRON_BIN_DIR/$NEUTRON_L3_BINARY $NEUTRON_CONFIG_ARG"
     fi
-    # XXX(sc68cal) - Here's where plugins can wire up their own networks instead
-    # of the code in lib/neutron_plugins/services/l3
-    if type -p neutron_plugin_create_initial_networks > /dev/null; then
-        neutron_plugin_create_initial_networks
-    else
-        # XXX(sc68cal) Load up the built in Neutron networking code and build a topology
-        source $TOP_DIR/lib/neutron_plugins/services/l3
-        # Create the networks using servic
-        create_neutron_initial_network
+    if is_service_enabled neutron-api; then
+        # XXX(sc68cal) - Here's where plugins can wire up their own networks instead
+        # of the code in lib/neutron_plugins/services/l3
+        if type -p neutron_plugin_create_initial_networks > /dev/null; then
+            neutron_plugin_create_initial_networks
+        else
+            # XXX(sc68cal) Load up the built in Neutron networking code and build a topology
+            source $TOP_DIR/lib/neutron_plugins/services/l3
+            # Create the networks using servic
+            create_neutron_initial_network
+        fi
     fi
     if is_service_enabled neutron-metadata-agent; then
         run_process neutron-metadata-agent "$NEUTRON_BIN_DIR/$NEUTRON_META_BINARY $NEUTRON_CONFIG_ARG"