Add yaml anchors as in gitlab training

[wdconinc]

https://hsf-training.github.io/hsf-training-cicd/03-understanding-yaml/index.html#anchors is absent in github tutorial.

More general question: how do we avoid divergence for these parallel episodes?

[klieret]

it's actually never used in the training... (neither here nor with gitlab). But I actually didn't know that and think it's pretty cool.

[stale]

This issue or pull request has been automatically marked as stale because it has not had recent activity. Please manually close it, if it is no longer relevant, or ask for help or support to help getting it unstuck. Let me bring this to the attention of @klieret @wdconinc @michmx for now.