### 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
public void testFetchAllPagesSearchHitCursorTxt() throws IOException {
        testFetchAllPagesSearchHitCursor("text/plain");
    }
    public void testFetchAllPagesSearchHitCursorCsv() throws IOException {
        testFetchAllPagesSearchHitCursor("text/csv");
    }
    public void testFetchAllPagesSearchHitCursorTsv() throws IOException {
        testFetchAllPagesSearchHitCursor("text/tab-separated-values");
    }
    public void testFetchAllPagesSearchHitCursor(String format) throws IOException {
        int size = randomIntBetween(4, 20);
        int pageSize = randomIntBetween(1, size + 1);
        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 FROM " + indexPattern("test") + " ORDER BY field", texts, pageSize, size % pageSize == 0);
    }
    /**
     * Special case of `testFetchAllPagesSearchHitCursorTxt` covering https:github.com/elastic/elasticsearch/issues/83788.
     */
    public void testFetchAllPagesSearchHitCursorWithNonFullLastPageTxt() throws IOException {
        int size = randomIntBetween(4, 20);
        int pageSize = size / 2 + 1;
        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("text/plain", "SELECT field FROM " + indexPattern("test") + " ORDER BY field", texts, pageSize, false);
    }
    public void testFetchAllPagesCompositeAggCursorTxt() throws IOException {
        testFetchAllPagesCompositeAggCursor("text/plain");
    }
    public void testFetchAllPagesCompositeAggCursorCsv() throws IOException {