if you check here: mod_fcgid - Apache HTTP Server Version 2.5
for the context in which this directive is available, you’ll find it be possible within vhost context too.
so you could create a custom apache conf file for your domain in the folder /home/<user>/conf/<yourdomain>/ with that line in it, so it will be included. name for custom configs should be apache2.conf_something and apache2.ssl.conf_something