fix: opensearch metadata filtering returns empty (#20701)

Co-authored-by: wenjun.gu <wenjun.gu@envision-energy.com>
Co-authored-by: crazywoola <427733928@qq.com>

api/core/rag/datasource/vdb/opensearch/opensearch_vector.py

                             Field.METADATA_KEY.value: {
                                 "type": "object",
                                 "properties": {
-                                    "doc_id": {"type": "keyword"}  # Map doc_id to keyword type
+                                    "doc_id": {"type": "keyword"},  # Map doc_id to keyword type
+                                    "document_id": {"type": "keyword"},
                                 },
                             },
                         }