Revert "Don't check for existing endpoints"

This reverts commit 7d1ec430046256ac3f536f4920a43936e28ef0c4.

This broke the sahara and layer4 dsvm jobs. The layer4 job
is voting on tempest changes so tempest is also broken.

Change-Id: Ide69f10cd85bf7ff0d86bc8cba56dedd26850362
Partial-Bug: #1573868
diff --git a/lib/swift b/lib/swift
index b74b4da..8cb94ef 100644
--- a/lib/swift
+++ b/lib/swift
@@ -633,7 +633,7 @@
     create_service_user "swift" "admin"
 
     get_or_create_service "swift" "object-store" "Swift Service"
-    create_endpoint \
+    get_or_create_endpoint \
         "object-store" \
         "$REGION_NAME" \
         "$SWIFT_SERVICE_PROTOCOL://$SERVICE_HOST:$SWIFT_DEFAULT_BIND_PORT/v1/AUTH_\$(project_id)s" \