RepartitionExec incorrectly reports metrics for all partitions against a single partition #10015

Describe the bug

@crepererum notes in in #10009 (comment)_

This was broken before: the first parameter was set to partition, i.e. the first partition that initializes the state. That's clearly wrong. I now initialize it to 0 and will fix the tracking properly in a follow-up PR.

To Reproduce

No response

Expected behavior

The metrics for each partition should be assigned to their individual partition

Additional context

Found on #10009