adding linuxbridge agent feature to neutron formula.

by this user will be able to enable linuxbridge agent insted of default openvswitch from cluster level.

Pillar changes are :

neutron:gateway:backend:mechanism:lb:driver = linuxbridge
neutron:compute:backend:mechanism:lb:driver = linuxbridge
neutron:gateway:agents:l3:interface_driver = linuxbridge

Closes-Bug: https://mirantis.jira.com/browse/PROD-24715

Change-Id: Ic1ca59155a1833eea928450fca8172321f88602d
diff --git a/tests/pillar/compute_linuxbridge.sls b/tests/pillar/compute_linuxbridge.sls
new file mode 100644
index 0000000..5c29787
--- /dev/null
+++ b/tests/pillar/compute_linuxbridge.sls
@@ -0,0 +1,26 @@
+neutron:
+  compute:
+    agent_mode: legacy
+    firewall_driver: iptables
+    backend:
+      engine: ml2
+      tenant_network_types: "flat,vxlan"
+      mechanism:
+        lb:
+          driver: linuxbridge
+    dvr: false
+    enabled: true
+    external_access: false
+    local_ip: 10.1.0.105
+    message_queue:
+      engine: rabbitmq
+      host: 127.0.0.1
+      password: workshop
+      port: 5672
+      user: openstack
+      virtual_host: /openstack
+    metadata:
+      host: 127.0.0.1
+      password: password
+      workers: 2
+    version: mitaka