insights: Remove all code for related insights prototype
Created by: CristinaBirkel
Closes https://github.com/sourcegraph/sourcegraph/issues/39365
Description
This prototype has been cancelled for now in order to focus our efforts on other things. As such, this PR removes all the code. We can always get it back from the history if needed.
Test plan
I did a bit of regression testing locally, and things seem to be working. This just rips out endpoints, the entire file that contained the resolvers, and some extra methods that are no longer being used. Also one change to the insight_store
GetAll
method that is also no longer being used.