rclone-backup: raise throughput now that we have our own Drive quota

With the dedicated client_id the shared-project rate limits are gone, so
lift the pacing: tpslimit 10->25 and drive-pacer-min-sleep 100ms->10ms
(the old 100ms capped requests at ~10/s and would have throttled the
higher tpslimit anyway).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/fileserver.nix

@@ -306,8 +306,8 @@
         ${pkgs.rclone}/bin/rclone sync /data gdrive:backup-daten \
           --fast-list \
           --drive-stop-on-upload-limit \
-          --tpslimit 10 \
-          --drive-pacer-min-sleep 100ms \
+          --tpslimit 25 \
+          --drive-pacer-min-sleep 10ms \
           --retries 3 \
           --log-file=/var/log/rclone-backup.log \
           --log-level=INFO