### Elasticsearch Version

main

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

MacOS

### Problem Description

When there are 2 or more concurrent `_update` requests issued, one of them may fail with `ResourceAlreadyExistsException` exception which is misleading.


### Steps to Reproduce

1. Spawn a number of `_update` requests at the same time
2. Look at the results of these requests
3. Observe `ResourceAlreadyExistsException` being thrown in the case of conflict

### Logs (if relevant)

_No response_
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/persistence/IndexBasedTransformConfigManager.java
indexRequest,
                ActionListener.wrap(r -> { listener.onResponse(true); }, e -> {
                    if (e instanceof VersionConflictEngineException) {
                        
                        listener.onFailure(
                            new ResourceAlreadyExistsException(
                                TransformMessages.getMessage(TransformMessages.REST_PUT_TRANSFORM_EXISTS, transformConfig.getId())
                            )
                        );
                    } else {
                        listener.onFailure(new RuntimeException(TransformMessages.REST_PUT_FAILED_PERSIST_TRANSFORM_CONFIGURATION, e));
                    }
                })
            );
        } catch (IOException e) {
            
            listener.onFailure(
                new ElasticsearchParseException(
                    TransformMessages.getMessage(TransformMessages.REST_FAILED_TO_SERIALIZE_TRANSFORM, transformConfig.getId()),
                    e
                )
            );
        }
    }
    @Override
    public void getTransformCheckpoint(String transformId, long checkpoint, ActionListener<TransformCheckpoint> resultListener) {
        QueryBuilder queryBuilder = QueryBuilders.termQuery("_id", TransformCheckpoint.documentId(transformId, checkpoint));
        SearchRequest searchRequest = client.prepareSearch(
            TransformInternalIndexConstants.INDEX_NAME_PATTERN,
            TransformInternalIndexConstants.INDEX_NAME_PATTERN_DEPRECATED