Geo: Replace Git over HTTP calls with new Workhorse HTTP endpoint for SSH

Overview

The general information can be found in Cells: SSH Routing for Git Pull and Push (&13532)

This issue is about using the Workhorse endpoint that serves bidirectional SSH data. The endpoint will be introduced in Workhorse: HTTP endpoint for bidirectional SSH ... (gitlab#456116 - closed). It requires making the experiment performed in this MR Draft: Poc: Use SSH RPC exposed by Workhorse (!969 - closed) production-ready.

First iteration

The PoC MR includes communication with Global Service, however, https://gitlab.com/gitlab-org/tenant-scale-group/pocs/global-service is in a state of internal PoC. For the first iteration, let's replace the existing Git over HTTP calls with the call to the new endpoint: Workhorse: HTTP endpoint for bidirectional SSH ... (gitlab#456116 - closed)