Adding back incremental queue metrics
Now that the queue is working well, add back incremental queue metrics.
Note.- A rollback was done in this PR https://github.com/huggingface/datasets-server/pull/1698/files

Adding back incremental queue metrics: Now that the queue is working well, add back incremental queue metrics.
Note.- A rollback was done in this PR https://github.com/huggingface/datasets-server/pull/1698/files
