Default apt upgrade to preserve configuration

Since Hestia tweaks config files of services, I think we should default to keeping that modified version in upgrades:

We could add this file by default: /etc/apt/apt.conf.d/force-confold

Dpkg::Options {
   "--force-confdef";
   "--force-confold";
}

This should also prevent accidental issues like Server's apache2 or nginx configurations got reset after apt upgrade - #3 by monk

I think that upgrade prompt is confusing and unnecessary for a lot of Hestia Admins and there seems to be only one right way to choose anyways.