insights: curate some basic test data for end to end tests

Created by: coury-clark

The code insights backend doesn't have any end-to-end tests right now. The first step to accomplishing something like this is to build a data set. We shouldn't aim to capture every possible edge case / use case, rather have something simple that we can do high-level validation that things aren't completely broken.

1. We can probably stick with a few repos for now (maybe 5)
2. Each repo should have a few commits within a 12 month range
3. We should use a common prefix such that we can easily filter the final result in a regex

Ultimately it would probably be useful to bake this into a tool that can generate the data.