Configure subnets CIDR for BGP tests

The patch configures CIDR for subnets used in BGP tests because
when these tests are run simulteniuosly they tries to use the same
CIDR and fail with error "Available CIDR for subnet creation could not be found".

Related-PRODX: PRODX-30128
Change-Id: Ibfd1dbbbfa77f71cddfb3f40bcab957da4bcb8e5
(cherry picked from commit f4753a1e98b0be1fd41806345d075fd688185ffd)
diff --git a/neutron_tempest_plugin/neutron_dynamic_routing/api/test_bgp_speaker_extensions.py b/neutron_tempest_plugin/neutron_dynamic_routing/api/test_bgp_speaker_extensions.py
index 5cdd524..b7e5c9e 100644
--- a/neutron_tempest_plugin/neutron_dynamic_routing/api/test_bgp_speaker_extensions.py
+++ b/neutron_tempest_plugin/neutron_dynamic_routing/api/test_bgp_speaker_extensions.py
@@ -229,6 +229,25 @@
     def test_get_advertised_routes_null_address_scope(self):
         self.useFixture(fixtures.LockFixture('gateway_network_binding'))
         bgp_speaker = self.create_bgp_speaker(**self.default_bgp_speaker_args)
+
+        addr_scope1 = self.create_address_scope(
+                                 'get-advertised-routes-null-address-scope',
+                                 ip_version=4)
+        ext_net = self.create_shared_network(**{'router:external': True})
+        ext_subnetpool = self.create_subnetpool(
+                                 'get-advertised-routes-null-address-pool-ext',
+                                 is_admin=True,
+                                 default_prefixlen=24,
+                                 address_scope_id=addr_scope1['id'],
+                                 prefixes=['8.0.0.0/8'])
+        self.create_subnet({'id': ext_net['id']},
+                   cidr=netaddr.IPNetwork('8.1.0.0/24'),
+                   ip_version=4,
+                   client=self.admin_client,
+                   subnetpool_id=ext_subnetpool['id'])
+        ext_gw_info = {'network_id': ext_net['id']}
+        router = self.create_router(ext_gw_info)
+        self.admin_routers.append(router)
         bgp_speaker_id = bgp_speaker['id']
         self.bgp_adm_client.add_bgp_gateway_network(bgp_speaker_id,
                                                   self.ext_net_id)
@@ -238,6 +257,21 @@
     @decorators.idempotent_id('cae9cdb1-ad65-423c-9604-d4cd0073616e')
     def test_get_advertised_routes_floating_ips(self):
         self.useFixture(fixtures.LockFixture('gateway_network_binding'))
+        addr_scope1 = self.create_address_scope(
+                                 'get-advertised-routes-floating-ip-scope',
+                                 ip_version=4)
+        ext_net = self.create_shared_network(**{'router:external': True})
+        ext_subnetpool = self.create_subnetpool(
+                                 'get-advertised-routes-floating-ip-ext',
+                                 is_admin=True,
+                                 default_prefixlen=24,
+                                 address_scope_id=addr_scope1['id'],
+                                 prefixes=['8.0.0.0/8'])
+        self.create_subnet({'id': ext_net['id']},
+                   cidr=netaddr.IPNetwork('8.2.0.0/24'),
+                   ip_version=4,
+                   client=self.admin_client,
+                   subnetpool_id=ext_subnetpool['id'])
         bgp_speaker = self.create_bgp_speaker(**self.default_bgp_speaker_args)
         bgp_speaker_id = bgp_speaker['id']
         self.bgp_adm_client.add_bgp_gateway_network(bgp_speaker_id,