Issue
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* See !1484 (comment 1643676118) for a description
  of the catch-22 situation we ended up in when the `test-vista` job ran both in the pre-merge and
  post-merge pipelines.

* In the pre-merge pipelines, one can proceed with the Merge even if the job fails.

* But in the post-merge pipeline, a failure in the `test-vista` job causes jobs in the next stage
  of the pipeline to not run and one of them is the job that pushes the updated `octo-vehu` image
  (which is what the `test-vista` job relies on as the source docker image).

Fix
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* The attempted fix is to run the `test-vista` job only in the pre-merge pipelines. That way one
  will know if there are any failures and fix it right away before the merge.

* But it is possible like was encountered in 4b1735f9 (!1484) where a change to YDBAIM needed
  to make its way to the `octo-vehu` imag...