### Elasticsearch Version

8.9.0

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

any

### Problem Description

If the context text supplied to the Question Answering task is longer than the model's `max_sequence_length` and `truncate` is set to `none` then inference on the model fails with the message:

```
status_exception: question answering result has invalid dimension, expected 2 found [6] 
```
<img width="1438" alt="Screenshot 2023-07-25 at 08 21 37" src="https://github.com/elastic/elasticsearch/assets/2353640/12d296f6-03b2-4cda-89ce-7399348c4104">


### Steps to Reproduce

Use long input text to the question answering task


### Work Aroundf
The fix is to truncate the context which unfortunately may remove the part of the document containing the answer. For reference the call is documented here

```
POST _ml/trained_models/distilbert-base-cased-distilled-squad/deployment/_infer
{
  "docs":[{ "text_field": "question answering context"}],
  "inference_config": {
    "question_answering": {
      "question": "The question to ask",
      "tokenization": {
        "bert": {
          "truncate": "second",
          "span": -1          
        }
      }
    }
  }
}
````

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/nlp/tokenizers/TokenizationResult.java
builder.endArray();
        }
        builder.endArray();
    }
    protected void writeAttentionMask(String fieldName, XContentBuilder builder) throws IOException {
        builder.startArray(fieldName);
        for (var inputTokens : tokens) {
            builder.startArray();
            
            for (int ignored : inputTokens.tokenIds) {
                builder.value(1);
            }
            for (int i = inputTokens.tokenIds.length; i < maxLength; i++) {
                builder.value(padTokenId);
            }
            builder.endArray();
        }
        builder.endArray();
    }
    protected void writeTokenTypeIds(String fieldName, XContentBuilder builder) throws IOException {
        builder.startArray(fieldName);
        for (var inputTokens : tokens) {
            builder.startArray();
            
            if (inputTokens.seqPairOffset <= 0) {
                for (int j = 0; j < maxLength; j++) {
                    builder.value(0);
                }
            } else {