Create VMs for l3vpn in own network

The L3VPN use-case allows to connect different subnets between locations.
The patch actualize address range for VMs to do not intersect with
remote location.

Related-Prod: PRODX-3456
Change-Id: Ifb3fef31929944791b7298847bc579e8d6b50d80
(cherry picked from commit 53ff8e73df59c6815c70e9fb1432284fbd15f08c)
(cherry picked from commit 647b8aa816e1d05890f3746a567fc4cf598d2c3e)
diff --git a/neutron_tempest_plugin/config.py b/neutron_tempest_plugin/config.py
index 2ba7ba5..8f3d6c0 100644
--- a/neutron_tempest_plugin/config.py
+++ b/neutron_tempest_plugin/config.py
@@ -187,6 +187,10 @@
                default=None,
                help=("IP Address/Mask, which will be used to "
                      "test the l3vpn connectivity.")),
+    cfg.StrOpt('l3vpn_subnet_cidr',
+               default="192.168.0.254/24",
+               help=("IP Address/Mask, which will be used as private network"
+                     "test the l3vpn connectivity.")),
     cfg.StrOpt('l2vpn_endpoint',
                default=None,
                help=("IP Address/Mask, which will be used to "