codeintel: Rewrite integration tester utility

Created by: efritz

I guess I removed 10k lines of CSV files...?

This effort is mainly a way to decouple the index generation from the upload/query testing. I've moved all index generation to bash scripts and we're now storing indexes in a bucket so that non code intel people (and code intel people not currently working on a particular indexer) do not need to generate the indexes of eleven (and more coming soon) large repositories from scratch to test the API surface.

@uwedeportivo please see if these instructions are adequate to replace the e2e code intel test for releasing going forward. If you can, try to run it given the current instructions in this branch and please let me know if you have any trouble.

This will close https://github.com/sourcegraph/sourcegraph/issues/10832.