Enable follower fetching verification in the cloud

[vuldin]

Who is this for and what problem do they have today?

Cloud customers have no way to verify their clients are fetching from the closest broker. We have vectorized_cluster_partition_bytes_fetched_from_follower_total, but this metric is not part of the public metrics cloud customers have access to.

What are the success criteria?

Cloud customers would be able to verify that their clients are pulling from the correct (closest) broker.

Why is solving this problem impactful?

It can be costly for customers to fetch data across zones/regions, and they want to verify this is being avoided.

JIRA Link: CORE-2973