Fix bug on Vector index creation

[fleray]

In https://github.com/couchbase-examples/vector-search-cookbook/blob/71780f4152b79e4bfb95aacd84f6bc856f5ea96e/capella-ai/RAG_with_Couchbase_Capella.ipynb at Creating or Updating Search Indexes section, replace buggy code:

# Create the Vector Index via SDK
try:
    scope_index_manager = (
        cluster.bucket(CB_BUCKET_NAME).scope(SCOPE_NAME).search_indexes()
    )

    # Check if index already exists
    existing_indexes = scope_index_manager.get_all_indexes()
    index_name = index_definition["name"]

    if index_name in [index.name for index in existing_indexes]:
        logging.info(f"Index '{index_name}' found")
    else:
        logging.info(f"Creating new index '{index_name}'...")

    # Create SearchIndex object from JSON definition
    search_index = SearchIndex.from_json(index_definition)

    # Upsert the index (create if not exists, update if exists)
    scope_index_manager.upsert_index(search_index)
    logging.info(f"Index '{index_name}' successfully created/updated.")

except Exception as e:
    logging.error(f"Index exists: {e}")

by something like:

# Create the Vector Index via SDK
try:
    scope_index_manager = (
        cluster.bucket(CB_BUCKET_NAME).scope(SCOPE_NAME).search_indexes()
    )

    # Check if index already exists
    existing_indexes = scope_index_manager.get_all_indexes()
    index_name = index_definition["name"]

    index_name = index_name[index_name.rfind('.')+1:]
    if index_name in [index.name for index in existing_indexes]:
        print(f"Index '{index_name}' found. Let's update it!")
        scope_index_manager.drop_index(index_name)
    else:
        print(f"Creating new index '{index_name}'...")

    # Create SearchIndex object from JSON definition
    search_index = SearchIndex.from_json(index_definition)

    # Upsert the index (create if not exists, update if exists)
    scope_index_manager.upsert_index(search_index)
    print(f"Index '{index_name}' successfully created/updated.")

except Exception as e:
    print(f"Index exists: {e}")