Keep in mind that changes in “/etc/init.d” files are not update-safe and might be overwritten by a follow-up update of your packages. Depending if you’re using systemd now or in the future they might stop working as well.
To make these changes more future-proof you could create a feature request to the maintainer of your used packages to allow changing these parameters more easily (via e.g. /etc/default/openvas-manager).