main: reopen /dev/console for user service manager

Now the console_fd of user service manager is 2. Even if LogTarget=console is set in /etc/systemd/user.conf,there is no log in the console.
This reopen the /dev/console, so the log of user service can be output in the console.

src/core/main.c

@@ -2819,6 +2819,7 @@ int main(int argc, char *argv[]) {
         } else {
                 /* Running as user instance */
                 arg_system = false;
+                log_set_always_reopen_console(true);
                 log_set_target(LOG_TARGET_AUTO);
                 log_open();