test(_mapdata): reset indentation [skip ci]

test/integration/v3001-py3/files/_mapdata/ubuntu-18.yaml

@@ -48,8 +48,8 @@ values:
       ext_pillar:
       - cmd_yaml: cat /etc/salt/yaml
       - stack:
-        - /path/to/stack1.cfg
-        - /path/to/stack2.cfg
+          - /path/to/stack1.cfg
+          - /path/to/stack2.cfg
       - reclass:
           inventory_base_uri: /etc/reclass
       file_roots: