Is your feature request related to a problem or challenge?

output_batches should be a common metric in all operators. If we include it into BaselineMetrics, this can be updated automatically through record_poll() utility:

However, now it is only included in the join metrics, and join operators are updating this output_batches metrics manually.

Describe the solution you'd like

1. Include output_batches metric into BaselineMetrics
2. Update output_batches inside record_poll()
3. Remove all manual output_batches updates inside join operators. (by searching for all occurrences of 'output_batches' in the codebase).

Describe alternatives you've considered

No response

Additional context

No response