[Haskell-http-client] Correct fix of no-content endpoints

Created by: ivanbakel

While the fix in #9916 correctly made endpoint types which did not produce content return the NoContent type, those endpoint still generated Produces instances with the wrong mime types due to not resetting the hasProduces variable. This corrects that fix so that the Produces instance for MimeNoContent is generated instead of any other instance.

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