### Elasticsearch Version

8.3.0

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

arm64

### Problem Description

When using the `_terms_enum` API, if remote clusters return failures, but the local cluster doesn't, a null exception is thrown:

```
{
  "error": {
    "root_cause": [
      {
        "type": "null_pointer_exception",
        "reason": "Cannot invoke \"java.util.List.add(Object)\" because \"shardFailures\" is null"
      }
    ],
    "type": "null_pointer_exception",
    "reason": "Cannot invoke \"java.util.List.add(Object)\" because \"shardFailures\" is null"
  },
  "status": 500
}
```

### Steps to Reproduce

Call the _terms_enum API with a remote cluster that will return failures, e.g. because of this bug: https://github.com/elastic/elasticsearch/issues/86187

### Logs (if relevant)

_No response_
x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/termsenum/action/TransportTermsEnumAction.java
} finally {
                listener = null;
            }
        }
    }
    class NodeTransportHandler implements TransportRequestHandler<NodeTermsEnumRequest> {
        @Override
        public void messageReceived(NodeTermsEnumRequest request, TransportChannel channel, Task task) throws Exception {
            asyncNodeOperation(request, task, ActionListener.wrap(channel::sendResponse, e -> {
                try {
                    channel.sendResponse(e);
                } catch (Exception e1) {
                    logger.warn(
                        () -> new ParameterizedMessage(
                            "Failed to send error response for action [{}] and request [{}]",
                            actionName,
                            request
                        ),
                        e1
                    );
                }
            }));
        }
    }
    private void asyncNodeOperation(NodeTermsEnumRequest request, Task task, ActionListener<NodeTermsEnumResponse> listener)
        throws IOException {
        
        request.startTimerOnDataNode();