OpenSearch Security plugin: DLS not applied on documents linked by has_child or has_parent relation

Summary

### Description A flaw was identified in the OpenSearch Security plugin's document-level security (DLS) implementation. DLS restrictions were not correctly applied to search queries that use has_parent or has_child join relations. This could allow an authenticated user to access document contents that should have been restricted by DLS rules. ### Impact An authenticated user with access to an index containing parent/child join relations could bypass DLS restrictions on documents linked by those relations, potentially accessing restricted document contents. This only affects clusters that use both DLS and the `join` field type on the same index. ### Patches This issue is fixed in OpenSearch `2.19.4` and `3.2.0`. ### Workarounds Avoid using the `join` field type on indices that are subject to DLS rules.