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/core/src/main/java/org/elasticsearch/xpack/core/transform/action/PreviewTransformAction.java
}
        @Override
        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
            return this.config.toXContent(builder, params);
        }
        public TransformConfig getConfig() {
            return config;
        }
        @Override
        public void writeTo(StreamOutput out) throws IOException {
            super.writeTo(out);
            this.config.writeTo(out);
        }
        @Override
        public int hashCode() {
            return Objects.hash(config);
        }
        @Override
        public boolean equals(Object obj) {
            if (obj == this) {
                return true;
            }
            if (obj == null || getClass() != obj.getClass()) {
                return false;
            }
            Request other = (Request) obj;
            return Objects.equals(config, other.config);
        }
    }
    public static class Response extends ActionResponse implements ToXContentObject {