This reverts commit c418b7bb.

Our CI builds do not use the Docker image, so adding the Dockerfile to
the filter does not make sense. In addition, the entry was missing in
generate-target-filters.py, so it would have been removed when the
filters were regenerated.

lantiq-xrx200 is currently marked as source-only in OpenWrt 23.05, as
the switch driver does not work correctly on Linux 5.15. Mark as broken
in Gluon as well until the issue is fixed.

Upstream PR: https://github.com/openwrt/openwrt/pull/13200

as well as the target itself

Co-authored-by: Jan-Niklas Burfeind <github@aiyionpri.me>

Re-add mikrotik target

Note that previous images were generic ones and as such no migration
path is provided other than manually flashing the image via config-mode.

The scripts directory contains most of our build system, so changing it
should trigger a build of all targets.