Add missing 'connect' wrapper

This was missed in change Ib789cd4d11a3d5dd01fcdb99822025b11bbc234e
("Don't rely on implicit autocommit")

Change-Id: I9ec27650ae5e36099a6d2b2d59bb66cd820e8ffc
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

oslo_db/sqlalchemy/utils.py

@@ -1162,7 +1162,9 @@ def get_non_ndbcluster_tables(connectable, skip_tables=None):
 
     params['database'] = connectable.engine.url.database
     query = text(query_str)
-    nonndbcluster = connectable.execute(query, **params)
+    # TODO(stephenfin): What about if this is already a Connection?
+    with connectable.connect() as conn, conn.begin():
+        nonndbcluster = connectable.execute(query, **params)
     return [i[0] for i in nonndbcluster]