Make the codeintel-qa test suite resilient to additional indexed repos

Created by: jhchabran

While working on #34278 (closed), we stumbled on a few issues, the first one being the auto-indexing being enabled which skewed the results. But one issue remains: the codeintel-qa script has not been designed to be run on a normal dataset, and therefore can clash with the presence of other repositories being indexed.

@efritz suggested this could be done and that we could reduce the testing dataset along the way.