[BUG] OpenSearch Serverless Sink does not create index on startup

[graytaylor0]

Describe the bug When using an OpenSearch Serverless collection in a pipeline in the opensearch sink, the index configured is not created until a document is sent to the pipeline and is indexed into the collection.

To Reproduce Steps to reproduce the behavior:

1. Create a pipeline with an opensearch serverless collection as a sink
2. Observe the index configured in the sink is not created when starting Data Prepper
3. Send an Event to the pipeline
4. Observe the document in the collection in the specified index

Expected behavior The index should be created on startup like it is for non-serverless opensearch sinks

Screenshots If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: [e.g. Ubuntu 20.04 LTS]
• Version [e.g. 22]

Additional context Add any other context about the problem here.