[test_server_signal] Add dependency between fip association and router_interface

Add explicit dependency between fip association and router interface addition
to the subnet with server.

Related-Prod: PRODX-41784
Change-Id: I7496fc93457ec978bfdaa7771d9ffb88fcdc1799
diff --git a/heat_tempest_plugin/tests/scenario/templates/test_server_signal.yaml b/heat_tempest_plugin/tests/scenario/templates/test_server_signal.yaml
index 90f1b47..4a6bffb 100644
--- a/heat_tempest_plugin/tests/scenario/templates/test_server_signal.yaml
+++ b/heat_tempest_plugin/tests/scenario/templates/test_server_signal.yaml
@@ -98,6 +98,7 @@
 
   server_floating_ip_assoc:
     type: OS::Neutron::FloatingIPAssociation
+    depends_on: router_interface
     properties:
       floatingip_id: {get_resource: floating_ip}
       port_id: {get_attr: [server, addresses, {get_resource: network}, 0, port]}