tool_operate: fix the suppression logic of some error messages

tool_operate: fix the suppression logic of some error messages

- Fix the failed truncation and failed writing body error messages to
  not be shown unless error messages are shown. (ie the user has
  specified -sS, or has not specified -s).

- Also prefix same error messages with "curl: ", for example:
  curl: (23) Failed to truncate, exiting

Prior to this change the failed truncation error messages would be shown
if not -s, but did not account for -sS which should show.

Prior to this change the failed writing body error messages would be
shown always.

Ref: https://curl.se/docs/manpage.html#-S

Bug: https://curl.se/mail/archive-2020-12/0017.html
Reported-by: Hongyi Zhao
Closes https://github.com/curl/curl/pull/6402