Add TFS-Git repository backend name to git client.
Review Request #13351 — Created Oct. 16, 2023 and submitted
The new repository matching algorithm in RBTools didn't include the
repository backend name for TFS-Git, which made it so posting changes
didn't work unless the repository was explicitly configured. This change
adds it so that RBTools can find matching repos.
Was able to post a change without having anything in my .reviewboardrc