enhance(tls): use go's tls defaults (#38687)

The hardcoded cipher suites and curve preferences date from 2021 and no
longer match what Go ships. All four `SSL_*` are now unset by default
which means "use Go's default".

1. TLS 1.3 is now the default instead of TLS 1.2.
2. Post-quantum key exchange (`X25519MLKEM768`) works.
3. Four `ECDHE-*-CBC-SHA` suites become negotiable on TLS 1.2.

modules/graceful/server.go

@@ -101,10 +101,6 @@ func (srv *Server) ListenAndServe(serve ServeFunction, useProxyProtocol bool) er
 func (srv *Server) ListenAndServeTLSConfig(tlsConfig *tls.Config, serve ServeFunction, useProxyProtocol, proxyProtocolTLSBridging bool) error {
 	go srv.awaitShutdown()
 
-	if tlsConfig.MinVersion == 0 {
-		tlsConfig.MinVersion = tls.VersionTLS12
-	}
-
 	listener, err := GetListener(srv.network, srv.address)
 	if err != nil {
 		log.Error("Unable to get Listener: %v", err)