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/test/java/org/elasticsearch/xpack/transform/transforms/pivot/PivotTests.java
assertValidTransform(client, source, pivot);
        }
    }
    public void testValidateAllUnsupportedAggregations() throws Exception {
        for (String agg : unsupportedAggregations) {
            AggregationConfig aggregationConfig = getAggregationConfig(agg);
            Function pivot = new Pivot(
                getValidPivotConfig(aggregationConfig),
                new SettingsConfig(),
                Version.CURRENT,
                Collections.emptySet()
            );
            pivot.validateConfig(ActionListener.wrap(r -> { fail("expected an exception but got a response"); }, e -> {
                assertThat(e, is(instanceOf(ValidationException.class)));
                assertThat(
                    "expected aggregations to be unsupported, but they were",
                    e.getMessage(),
                    containsString("Unsupported aggregation type [" + agg + "]")
                );
            }));
        }
    }
    public void testGetPerformanceCriticalFields() throws IOException {
        String groupConfigJson = """
            {
              "group-A": {
                "terms": {
                  "field": "field-A"
                }
              },