`orderby` param of `include` passed with no `include` value

### Description of the bug

On load, a block can send a request that looks like this: `/wp-json/wp/v2/posts?context=edit&offset=0&orderby=include&per_page=1&type=announcement&include=&_locale=user`
which returns
```
{
"code": "rest_orderby_include_missing_include",
"message": "You need to define an include parameter to order by include.",
"data": {
"status": 400
}
}
```

### Steps To Reproduce

Set up a Query block with a query that will return no posts.
The backfill request will be sent passing either null or commas (depending on the number of posts) as the `include` parameter.

### Additional Information

_No response_