nixos/github-runners: use Runner.Listener directly for registration

Nothing the script `config.sh` does prior to the final call to
`Runner.Listener configure` is relevant for the systemd service.
Particularly, we don't need (nor want) any of the artifacts the `env.sh`
script creates.

nixos/modules/services/continuous-integration/github-runner/service.nix

@@ -149,7 +149,7 @@ in
               else
                 args+=(--token "$token")
               fi
-              ${cfg.package}/bin/config.sh "''${args[@]}"
+              ${cfg.package}/bin/Runner.Listener configure "''${args[@]}"
               # Move the automatically created _diag dir to the logs dir
               mkdir -p  "$STATE_DIRECTORY/_diag"
               cp    -r  "$STATE_DIRECTORY/_diag/." "$LOGS_DIRECTORY/"