feat: add batcher queue len and queue size in bytes metrics

[JulianVentura]

Add batcher queue len and queue size in bytes metrics

Description

This PR adds two new metrics for the batcher:

• Queue length: The number of proofs waiting in the batcher's queue to be included in a batch
• Queue size: The sum of the sizes of the verification data, measured in bytes, of the proofs waiting in the batcher's queue.

How to test

1. Start all services locally, including the metrics
2. Start sending proofs
3. Go to the "System Data" dashboard and go to the bottom on the left size (the batcher side). You should see four new graphs showing the queue len and queue size.
4. Stop sending proofs and the metrics should be reset back to zero.
5. Send a burst of many proofs to see a spike in the graphs with make batcher_send_sp1_burst BURST_SIZE=23

Type of change

Please delete options that are not relevant.

• New feature
• Bug fix
• Optimization
• Refactor

Checklist

• “Hotfix” to testnet, everything else to staging
• Linked to Github Issue
• This change depends on code or research by an external entity
  • Acknowledgements were updated to give credit
• Unit tests added
• This change requires new documentation.
  • Documentation has been added/updated.
• This change is an Optimization
  • Benchmarks added/run
• Has a known issue
  • Link to the open issue addressing it
• If your PR changes the Operator compatibility (Ex: Upgrade prover versions)
  • This PR adds compatibility for operator for both versions and do not change batcher/docs/examples
  • This PR updates batcher and docs/examples to the newer version. This requires the operator are already updated to be compatible

[MarcosNicolau]

I think it makes sense to this logic to aligned-batcher/metrics.rs and do:

Suggested change

	self.metrics.queue_len.set(queue_len as i64);
	self.metrics.queue_size_bytes.set(queue_size_bytes as i64);
	self.metrics.update_queue_metrics(queue_len, queue_size_bytes);

Mostly because they are "measuring the same" and we always want to update them simultaneously.

[JulianVentura]

Yes, I think it's a good idea 👌🏻

[MarcosNicolau]

You haven't updated the grafana json! Thou I added them myself and it does seem to be working fine.

[JuArce]

There is missing to update the grafana dashbaord

[uri-99]

Lol yes missing graphana visualizations

[JulianVentura]

Sorry! Grafana dashboard was just added @uri-99 @JuArce @MarcosNicolau

[PatStiles]

Worked locally for me!

[uri-99]

i think these 2 new boxes in grafana are quite informative, yet they ended up quite in the bottom of the dashboard. i would put them a bit higher