set index name to default

Co-authored-by: Sebastian Husch Lee <10526848+sjrl@users.noreply.github.com>

Author: daric93

integrations/valkey/src/haystack_integrations/document_stores/valkey/document_store.py

@@ -155,7 +155,7 @@ def __init__(
         # Document store operation configuration
         batch_size: int = 100,
         # Index and vector configuration
-        index_name: str = "haystack_document",
+        index_name: str = "default",
         distance_metric: Literal["l2", "cosine", "ip"] = "cosine",
         embedding_dim: int = 768,
         metadata_fields: dict[str, type[str] | type[int]] | None = None,