Swap parameters to create users in domain tempest

Related-prod: PRODX-31274
Change-Id: I5c7e2b016d561a0376cbd46760743ee9fda36eaa
diff --git a/tempest/lib/common/dynamic_creds.py b/tempest/lib/common/dynamic_creds.py
index cbac5a6..3faef1b 100644
--- a/tempest/lib/common/dynamic_creds.py
+++ b/tempest/lib/common/dynamic_creds.py
@@ -113,8 +113,8 @@
         self.creds_domain_name = None
         if self.identity_version == 'v3':
             self.creds_domain_name = (
-                self.default_admin_creds.project_domain_name or
-                self.credentials_domain)
+                self.credentials_domain or
+                self.default_admin_creds.project_domain_name)
         self.creds_client = cred_client.get_creds_client(
             self.identity_admin_client,
             self.tenants_admin_client,