[BUG] Fix stats in PulsarZooKeeperClient multi.

[zhaizhibo]

Motivation

In PulsarZooKeeperClient.multi(), the stats were incorrectly using createStats instead of multiStats.

Modifications

Changed createStats to multiStats in the multi() method.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

[zhaizhibo]

/pulsarbot rerun

[merlimat]

Looks good. please add a test to verify we're passing the right stats object.