Update customer issues process

Created by: pecigonzalo

I would like to ensure all customer issues are tracked and created in GitHub. Right now, some issues are created, some are in other tracking systems, which makes it difficult to analyze the types of issues we have, or how many there are, etc.

As most of our workflow is already in GitHub, I think it will be a good idea to continue to do it here, as we can benefit from adding issues to labels, projects and milestones, as well as cross-link them to PRs or other issues. We could, for example, use labels to categorize issues.

The downside of using GitHub is that there is no out of the box tool to analyze the data for any MTTR or other types of report. Given those are not required at the moment, I dont think it will be a problem.

Relates to: https://github.com/sourcegraph/sourcegraph/issues/11904