Spread matching partitions across nodes

[dnr]

What changed?

Add option to use LookupN instead of Lookup for matching partition routing.

Why?

This can help spread partitions across available nodes better: instead of placing each partition independently, they're always placed on separate nodes, as long as there are enough nodes, up to the batch size.

How did you test it?

added unit test, will use cicd to test with this setting

Potential risks

If this dynamic config is changed on a live cluster, it may result in a period of task queue thrashing and delayed tasks. If changing on a live cluster, try to change on all nodes at the same time.