fix: ensure deleted chunks are not returned in retrieval (#12520) (#12546)

## Summary
Fixes #12520 - Deleted chunks should not appear in retrieval/reference
results.

## Changes

### Core Fix
- **api/apps/chunk_app.py**: Include \doc_id\ in delete condition to
properly scope the delete operation

### Improved Error Handling
- **api/db/services/document_service.py**: Better separation of concerns
with individual try-catch blocks and proper logging for each cleanup
operation

### Doc Store Updates
- **rag/utils/es_conn.py**: Updated delete query construction to support
compound conditions
- **rag/utils/opensearch_conn.py**: Same updates for OpenSearch
compatibility

### Tests
- **test/testcases/.../test_retrieval_chunks.py**: Added
\TestDeletedChunksNotRetrievable\ class with regression tests
- **test/unit/test_delete_query_construction.py**: Unit tests for delete
query construction

## Testing
- Added regression tests that verify deleted chunks are not returned by
retrieval API
- Tests cover single chunk deletion and batch deletion scenarios

api/apps/chunk_app.py

@@ -223,7 +223,9 @@ async def rm():
             e, doc = DocumentService.get_by_id(req["doc_id"])
             if not e:
                 return get_data_error_result(message="Document not found!")
-            if not settings.docStoreConn.delete({"id": req["chunk_ids"]},
+            # Include doc_id in condition to properly scope the delete
+            condition = {"id": req["chunk_ids"], "doc_id": req["doc_id"]}
+            if not settings.docStoreConn.delete(condition,
                                                 search.index_name(DocumentService.get_tenant_id(req["doc_id"])),
                                                 doc.kb_id):
                 return get_data_error_result(message="Chunk deleting failure")