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/action/TransportValidateTransformAction.java
this.clusterService = clusterService;
        this.transportService = transportService;
        this.nodeSettings = settings;
        this.sourceDestValidator = new SourceDestValidator(
            indexNameExpressionResolver,
            transportService.getRemoteClusterService(),
            DiscoveryNode.isRemoteClusterClient(settings)
                
                ? new RemoteClusterLicenseChecker(client, null)
                : null,
            ingestService,
            clusterService.getNodeName(),
            License.OperationMode.BASIC.description()
        );
    }
    @Override
    protected void doExecute(Task task, Request request, ActionListener<Response> listener) {
        final ClusterState clusterState = clusterService.state();
        if (request.isDeferValidation() == false) {
            TransformNodes.throwIfNoTransformNodes(clusterState);
            boolean requiresRemote = request.getConfig().getSource().requiresRemoteCluster();
            if (TransformNodes.redirectToAnotherNodeIfNeeded(
                clusterState,
                nodeSettings,
                requiresRemote,
                transportService,
                actionName,
                request,
                Response::new,
                listener