Use base.create_domain to create domain in testcases

This is to add **kwargs in base.create_domain, in order that
it can be more widely used in testcases, so to make code clean.

Change-Id: I0ed9102bd9d535b40467e9bf4600a291bfca0fc2
diff --git a/tempest/api/identity/admin/v3/test_domains.py b/tempest/api/identity/admin/v3/test_domains.py
index 86a5764..9683e93 100644
--- a/tempest/api/identity/admin/v3/test_domains.py
+++ b/tempest/api/identity/admin/v3/test_domains.py
@@ -31,10 +31,7 @@
         # One of those domains will be disabled
         cls.setup_domains = list()
         for i in range(3):
-            domain = cls.domains_client.create_domain(
-                name=data_utils.rand_name('domain'),
-                description=data_utils.rand_name('domain-desc'),
-                enabled=i < 2)['domain']
+            domain = cls.create_domain(enabled=i < 2)
             cls.setup_domains.append(domain)
 
     @classmethod