Get instance of an existing Neo4j relationship vector index.
This method will return the instance of the store without
inserting any new embeddings.
Neo4j credentials are required in the form of url, username,
and password and optional database parameters along with
the index_name definition.
from_existing_relationship_index(
cls: Type[Neo4jVector],
embedding: Embeddings,
index_name: str,
search_type: SearchType = DEFAULT_SEARCH_TYPE,
embedding_dimension: Optional[int] = None,
**kwargs: Any = {}
) -> Neo4jVector