OpenSearchDocumentStore.delete_index breaks if index does not exist

[tstadel]

Describe the bug
OpenSearchDocumentStore.delete_index breaks if index does not exist.
Usually delete_index does not raise when index does not exist. With newly introduced IVF feature this has changed.

Error message

Traceback (most recent call last):
   ...
    document_store.delete_index(index=document_store.index)
  File "/opt/venv/lib/python3.10/site-packages/haystack/document_stores/opensearch.py", line 748, in delete_index
    index_mapping = self.client.indices.get(index)[index]["mappings"]["properties"]
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/client/utils.py", line 178, in _wrapped
    return func(*args, params=params, headers=headers, **kwargs)
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/client/indices.py", line 197, in get
    return self.transport.perform_request(
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/transport.py", line 408, in perform_request
    raise e
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/transport.py", line 369, in perform_request
    status, headers_response, data = connection.perform_request(
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/connection/http_urllib3.py", line 266, in perform_request
    self._raise_error(
  File "/opt/venv/lib/python3.10/site-packages/opensearchpy/connection/base.py", line 301, in _raise_error
    raise HTTP_EXCEPTIONS.get(status_code, TransportError)(
opensearchpy.exceptions.NotFoundError: NotFoundError(404, 'index_not_found_exception', 'no such index [...]', ..., index_or_alias)

Expected behavior
delete_index does not raise if index does not exist.

To Reproduce
Call delete_index on OpenSearchDocumentStore for non existing index

FAQ Check

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System:

• OS:
• GPU/CPU:
• Haystack version (commit or version number): 1.14.0
• DocumentStore:
• Reader:
• Retriever: