Remove “This incident will be reported.” from user warnings
This change was partly reverted in <a href="https://github.com/sudo-project/sudo/commit/9757d29a24ac1872872cf09757b0439c54089707">https://github.com/sudo-project/sudo/commit/9757d29a24ac1872...</a><p>TL;DR: Only display the warning if sudo is configured to send emails.