Refactor cleanup steps to use cleanup_lxc function (#9354)

install/apt-cacher-ng-install.sh

@@ -16,7 +16,7 @@ update_os
 msg_info "Installing Apt-Cacher NG"
 DEBIAN_FRONTEND=noninteractive $STD apt-get -o Dpkg::Options::="--force-confold" install -y apt-cacher-ng
 sed -i 's/# PassThroughPattern: .* # this would allow CONNECT to everything/PassThroughPattern: .*/' /etc/apt-cacher-ng/acng.conf
-cat << EOF >/etc/apt/apt.conf.d/00aptproxy.conf
+cat <<EOF >/etc/apt/apt.conf.d/00aptproxy.conf
 Acquire::http::Proxy "http://localhost:3142";
 EOF
 systemctl enable -q --now apt-cacher-ng
@@ -24,8 +24,4 @@ msg_ok "Installed Apt-Cacher NG"
 
 motd_ssh
 customize
-
-msg_info "Cleaning up"
-$STD apt-get -y autoremove
-$STD apt-get -y autoclean
-msg_ok "Cleaned"
+cleanup_lxc