The temporary pipeline has to be referenced with `search_pipeline` instead of `pipeline` in the JSON.
Otherwise, you get the error `{"error":{"root_cause":[{"type":"parsing_exception","reason":"Unknown key for a START_OBJECT in [pipeline].","line":8,"col":16}],"type":"parsing_exception","reason":"Unknown key for a START_OBJECT in [pipeline].","line":8,"col":16},"status":400}`.
Tested with Docker image `opensearchproject/opensearch:2.11.0`.
Signed-off-by: Tim Vossen <61426691+upwards-gravity@users.noreply.github.com>