nginx client_body_buffer_size

[justinrush]

Since you expose nginx.config.client_max_body_size as a top level config it is probably best to also expose the client_body_buffer_size so folks can control what ends up being disk buffered and what doesn't. In addition to the performance benefit, setting that value high enough will also help prevent things like falco from endlessly complaining about unauthorized disk accesses.

In our environment I add the directive to: .nginx.config.httpSnippet. That works fine, but at first I had this as a top level config setting since I saw the other one in there.