Columnar scaling from 4 to 8 nodes is hung since 6+ hours.

1. Create a 3 node provisioned cluster, a magma bucket, 4 collections and load 20M items in each collection.
2. Create columnar instance with 2 nodes.
3. Create 4 remote collection each ingesting 20M items.
4. Ingestion completed.
5. Start an upsert kv workload on provisioned cluster.
6. Start query workload.
7. Scale Columnar from 2 -> 4. Successful.
8. Scale Columnar from 4 -> 8. Hang

cc: Murtadha Hubail, this is the hang I was referring to you over the chat.