Small fix at prepare.sh in case there are 2 admin users

Related-PROD: PROD-37187
Change-Id: I166aafd7bbdb6925c9f19f9c7782dbac399a3b6a
diff --git a/scripts/prepare.sh b/scripts/prepare.sh
index cdf6b12..1640dd3 100644
--- a/scripts/prepare.sh
+++ b/scripts/prepare.sh
@@ -16,6 +16,7 @@
 user=${name_prefix}.user
 admin=${name_prefix}.admin
 password=mcp1234
+domain=${OS_PROJECT_DOMAIN_NAME}
 
 # Security group
 sg_all=${name_prefix}.sg.all
@@ -192,7 +193,7 @@
 
 function _project() {
     echo project create ${project} >>${cmds}
-    admin_username=$(openstack user list --project admin -c Name -f value | grep admin)
+    admin_username=$(openstack user list --project admin --domain ${domain} -c Name -f value | grep admin)
     echo role add --user ${admin_username} --project ${project} admin >>${cmds}
 }