[Backport 8.18] Handle lists in copy_to field option correctly (Fixes #2992) (#2995)

* Handle lists in `copy_to` field option correctly (Fixes #2992) (#2993)

* Handle lists in `copy_to` field option correctly (Fixes #2992)

* add integration test

(cherry picked from commit 44cbf67)

* update generated files

---------

Co-authored-by: Miguel Grinberg <miguel.grinberg@gmail.com>

Author: github-actions[bot]

elasticsearch/dsl/aggs.py

@@ -678,9 +678,8 @@ class CategorizeText(Bucket[_R]):
     :arg categorization_analyzer: The categorization analyzer specifies
         how the text is analyzed and tokenized before being categorized.
         The syntax is very similar to that used to define the analyzer in
-        the [Analyze endpoint](https://www.elastic.co/guide/en/elasticsear
-        ch/reference/8.0/indices-analyze.html). This property cannot be
-        used at the same time as categorization_filters.
+        the `_analyze` endpoint. This property cannot be used at the same
+        time as categorization_filters.
     :arg shard_size: The number of categorization buckets to return from
         each shard before merging all the results.
     :arg size: The number of buckets to return. Defaults to `10` if