2.12.1 wants to change preferred-install option where order matters

I updated from 2.11.0 to 2.12.1 and now the normalization asks for this change

```diff
     "config": {
         "preferred-install": {
-            "acme/*": "source",
-            "*": "dist"
+            "*": "dist",
+            "acme/*": "source"
         },
```

This is wrong as the order matters in this config, see https://getcomposer.org/doc/06-config.md#preferred-install
