### Description

Only "search hits" based queries (no aggregations) provide a consistent view on the data when paginating through the result set. With point-in-time, it is possible to support transactional semantics for aggregation queries as well.

This issue is somewhat blocked by https://github.com/elastic/elasticsearch/issues/75528 because a PIT can not immediately be closed if the aggregation result set contains less than `fetch_size` records. This could cause some increased resource utilization due to open PITs. Especially if the client does not close the SQL cursor.
x-pack/plugin/sql/qa/server/src/main/java/org/elasticsearch/xpack/sql/qa/rest/RestSqlTestCase.java
List<String> texts = IntStream.range(0, size).mapToObj(i -> String.format(Locale.ROOT, "text%02d", i)).toList();
        index(texts.stream().map(t -> "{\"field\": \"" + t + "\"}").toArray(String[]::new));
        testFetchAllPages(
            format,
            "SELECT field, COUNT(*) c FROM " + indexPattern("test") + " GROUP BY field HAVING c = 1 ORDER BY field",
            texts,
            pageSize,
            true
        );
    }
    public void testFetchAllPagesListCursorTxt() throws IOException {
        testFetchAllPagesListCursor("text/plain");
    }
    public void testFetchAllPagesListCursorCsv() throws IOException {
        testFetchAllPagesListCursor("text/csv");
    }
    public void testFetchAllPagesListCursorTsv() throws IOException {
        testFetchAllPagesListCursor("text/tab-separated-values");
    }
    public void testFetchAllPagesListCursor(String format) throws IOException {
        int size = randomIntBetween(4, 20);
        int pageSize = randomIntBetween(1, size + 1);
        List<String> fields = IntStream.range(0, size).mapToObj(i -> String.format(Locale.ROOT, "text%02d", i)).toList();
        index(fields.stream().map(f -> "{\"" + f + "\": 1}").toArray(String[]::new));
        testFetchAllPages(format, "SHOW COLUMNS FROM " + indexPattern("test"), fields, pageSize, false);
    }
    /**
     * Generic paging test that ensures that
     * 1. All expected documents are fetched when scrolling through all pages
     * 2. There are at most `expectedValues.size() / pageSize + 1` pages (the last one might or might not be empty)