Revamp, test and monitor the local git-repo mirror

We set up at some point a local git-repo mirror - more details you can find in the docs here: https://gitlab.eclipse.org/eclipse/oniro-core/oniro/-/blob/kirkstone/docs/ci/hidden-jobs/workspace.rst#L111. The publishing side of it looks down. This is an important optimization build step so we want it:

1. fixed and brought back up
2. tested
3. monitored and maintained