The additional-networks connect loop in the kakaotalk systemd unit
template iterated over matrix_appservice_discord_container_additional_networks,
a copy-paste leftover from the discord bridge role. The host-network
guard added in #5310 mirrored the same wrong variable.

This means the kakaotalk container was being connected to the networks
computed for the discord bridge instead of its own, potentially leaving
it without access to its homeserver/database networks depending on the
discord bridge's configuration.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>