Create floating ip by normal user

In real use case, it should be the end user who will create floating
ip and associate with loadbalancer vip.

Also use config_drive when creating backend server, to keep consistent
with amphora creation in octavia itself.

Tested in devstack.

Change-Id: I2cbee37f494a5775a96f8c285f0e52c0b2550d5b
diff --git a/octavia_tempest_plugin/tests/server_util.py b/octavia_tempest_plugin/tests/server_util.py
index 2500195..54fa4f8 100644
--- a/octavia_tempest_plugin/tests/server_util.py
+++ b/octavia_tempest_plugin/tests/server_util.py
@@ -208,9 +208,13 @@
             if wait_until is None:
                 wait_until = 'ACTIVE'
 
-    body = clients.servers_client.create_server(name=name, imageRef=image_id,
-                                                flavorRef=flavor,
-                                                **kwargs)
+    body = clients.servers_client.create_server(
+        name=name,
+        imageRef=image_id,
+        flavorRef=flavor,
+        config_drive=True,
+        **kwargs
+    )
     server = rest_client.ResponseBody(body.response, body['server'])
 
     def _setup_validation_fip():