Bulk indexing: Fix 8125 hanged request when auto create index is off.

If a bulk request contains a mix of indexing requests for an existing index and one that needs to be auto-created but a cluster configuration prevents the auto-create of the new index, the ingest process hangs. The exception for the failure to create an index was not caught or reported back properly. Added a Junit test to recreate the issue and the associated fix is in TransportBulkAction.

Closes #8125
I think we simplify this code by merging the two use cases. The only difference is the exception that goes into the BulkItemResponse.Failure object. Can we have that as a variable instead of isClosed , i.e., `Exception unavailableException = null` and later check:

```
 if (unavailableException != null) {
             BulkItemResponse.Failure failure = new BulkItemResponse.Failure(request.index(), request.type(), request.id(), unavailableException);
             BulkItemResponse bulkItemResponse = new BulkItemResponse(idx, "index", failure);
             responses.set(idx, bulkItemResponse);
             // make sure the request gets never processed again
             bulkRequest.requests.set(idx, null);
         }
```