Clean up tmpfiles snippet
- Remove entries for passwd and friends, these will already be populated by systemd-sysusers before tmpfiles has a chance to run so these entries don't actually do anything.
- Remove entries for files that only have comments in them. These files only end up cluttering /etc making it harder to figure out what's local admin configuration at a glance.
- Symlink all other files that actually do something instead of copying them. By copying them, we will never receive any updates if the files are updated in /usr/share/factory/etc as tmpfiles will only copy the files if they don't exist in /etc already. By symlinking instead of copying, any updates to /usr/share/factory/etc will automatically be taken into account.