Incorrect behaviour of MultiFieldQueryNodeProcessor when default operator is 'AND' [LUCENE-3355]

StandardQueryNodeProcessorPipeline runs MultiFieldQueryNodeProcessor before GroupQueryNodeProcessor.

MultiFieldQueryNodeProcessor, if it encounters a node with no field, will do this:

```Java
return new GroupQueryNode(new BooleanQueryNode(children));
```

GroupQueryNodeProcessor comes along later on, sees that no operator is specified, so it applies the default operator, which, if set to 'AND', results in:

```Java
+properties:text +text:text
```

Which I don't think matches the intent of the multi-field processor.

---
Migrated from [LUCENE-3355](https://issues.apache.org/jira/browse/LUCENE-3355) by Trejkaz, updated Jan 23 2014

Start with StandardQueryNodeProcessorPipeline and inspect the interaction between MultiFieldQueryNodeProcessor and GroupQueryNodeProcessor when a node has no field. Reproduce the query with the default operator set to AND and verify that the resulting query matches the intended multi-field behavior without the unintended operator application.

Written by the indexing model from the issue text.