refactor: remove dead code from FAISSDocumentStore (#3372)

Author: anakin87

haystack/document_stores/faiss.py

@@ -204,8 +204,6 @@ def _create_new_index(
             index = faiss.IndexHNSWFlat(embedding_dim, n_links, metric_type)
             index.hnsw.efSearch = ef_search
             index.hnsw.efConstruction = ef_construction
-            if "ivf" in index_factory.lower():  # enable reconstruction of vectors for inverted index
-                self.faiss_indexes[index].set_direct_map_type(faiss.DirectMap.Hashtable)
 
             logger.info(
                 f"HNSW params: n_links: {n_links}, efSearch: {index.hnsw.efSearch}, efConstruction: {index.hnsw.efConstruction}"