lists: fix increased priority from l10n packages

Standard for_l10n function provided by root updater script is creating requests with default priority 50. This effectively increases priority of all packages using it to include their languages.

The solution here is to decrease priority for language packages to something very small (10 was chosen).

Also because we had to have copy of for_l10n function in bootstrap it was instead moved from there to utils and provided as our own version instead of updater's one. Original function can potentially be dropped later on as Turris lists are no longer using it thanks to this change.

This fixes uninstalls in firewall list. Those do not work because of elevated priority for Foris and Luci package thanks to translations.

cc: @mhrusecky