Elasticsearch / OpenSearch brownfield function does not incorporate meta

[tstadel]

Describe the bug
elasticsearch_index_to_document_store incorrectly sets the metadata after calling the constructor of Document. That way, Document's id does not incorporate the meta even though id_hash_keys contains meta key.

Expected behavior
meta is incorporated if id_hash_keys contain 'meta'.

To Reproduce

1. Ensure your source index contains docs with same contents, but different metas.
2. run

target_ds = OpenSearchDocumentStore(duplicate_documents="fail", ...)
open_search_index_to_document_store(
    document_store=target_ds, 
    original_index_name=index, 
    original_content_field="content", 
    host=host, 
    username=username, 
    password=password, 
    port=443,
    id_hash_keys=["content", "meta"]
)

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