Handling for 413 entity too large in BulkIndexer

While investigating https://github.com/elastic/ingest-dev/issues/3677, I noticed that this package does not handle a 413 Entity Too Large status from Elasticsearch. Even with batching, in specific use cases like in Beats (which may include large stack traces in documents), a batch can still exceed http.max_content_length, the maximum request size in Elasticsearch, which defaults to 100MB.

Start by tracing how BulkIndexer sends batches and handles Elasticsearch responses. Reproduce or inspect the 413 Entity Too Large case described in the issue, then define and verify the expected handling for batches exceeding Elasticsearch's http.max_content_length.

Written by the indexing model from the issue text.