Repurpose `project` for job name

- `codebase` isn't really working as expected, and `project` appears to
  be unused in multibuild

lib/worker_multibuild.py

@@ -217,8 +217,7 @@ def trigger_child_hooks(buildbotUrl: str, repository, branch, revision,
         request_data["changes"] = {
             "author": "buildbot_multibuild",
             "repository": repository,
-            "project": "/".join(repository.split("/")[-2:]),
-            "codebase": job,
+            "project": job,
         }
 
         retval = requests.post(request_url, headers=request_headers,