fix(handlers): support http.prefix for gitlab v1 routes
Related to: #866 (closed)
This MR adds support for the http prefix configuration option for GitLab V1 routes. While this isn't an option that we use, this step helps ensure that we have a smooth path towards a unified chi router as part of Replace the Router used for API Requests (&9467). Handling the prefix the same for all API routes will allow us to use a single root router for both the V2 and V1 APIs.