tls-gnutls.c: Revert the option change in `gnutls_bye`

Revert to the code from PR #365, because some TLS 1.2 implementations (e.g. Windows Server 2022) do not follow the standard properly, and sticking to standard would cause 20s-30s delays in printing over TLS.

With this change, both our TLS implementations behave the same - OpenSSL uses this option by default and it is not possible to change it, while GNUTLS provides this option to configure the closing behavior.