Code review comment for ~npochet/charm-sysconfig:fix-unnecessary-grub

I'm going to pick this up. I'd really like to see this functionality moved to the library and added unittests to ensure that the logic is being processed correctly. As I review the code for syshelper.charm_config, I see that is deprecated and shouldn't be the only source for determining the running of grub, as there are now also grub_config_flags to check.