A preview call can be quite expensive and cause timeout in a cluster. As a short term fix we identified 2 (hopefully) small fixes:

- make the call cancellable, the main issue here seems to be that preview calls search without using a parent task id(see this fix for data feeds: https://github.com/elastic/elasticsearch/pull/88142/files#diff-aba58244cb8f9dfa3ac3b6efeb02259e3d5956576f56c1ff5e243dd2aac27381)
- pass the timeout parameter of the preview call to the search call, currently a timeout can be specified, but is ignored for the inner search call, which is executed with no timeout (see https://www.elastic.co/guide/en/elasticsearch/reference/master/search-search.html#search-search-api-query-params).

Both changes are bugs and shall be relatively simple to implement and considered for backport to the 7.17 branch.

@przemekwitek can you have a look at this?

related: #88010
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/common/AbstractCompositeAggFunction.java
listener.onResponse(true);
        }, e -> {
            Throwable unwrapped = ExceptionsHelper.unwrapCause(e);
            RestStatus status = unwrapped instanceof ElasticsearchException
                ? ((ElasticsearchException) unwrapped).status()
                : RestStatus.SERVICE_UNAVAILABLE;
            listener.onFailure(
                new ValidationException(unwrapped).addValidationError(format("Failed to test query, received status: %s", status))
            );
        }));
    }
    @Override
    public Tuple<Stream<IndexRequest>, Map<String, Object>> processSearchResponse(
        SearchResponse searchResponse,
        String destinationIndex,
        String destinationPipeline,
        Map<String, String> fieldTypeMap,
        TransformIndexerStats stats,
        TransformProgress progress
    ) {
        Aggregations aggregations = searchResponse.getAggregations();
        
        
        if (aggregations == null) {
            return null;
        }
        CompositeAggregation compositeAgg = aggregations.get(COMPOSITE_AGGREGATION_NAME);
        if (compositeAgg == null || compositeAgg.afterKey() == null) {
            return null;
        }