More than 1 collection of indexes being built in parallel during rebalance on a new node

WRT to MB-57057

Build -> 7.2.1-5878

I have observed during a swap rebalance that the indexes of multiple collections are being built in parallel. 

Steps to reproduce the issue

1. Create a cluster with 3 nodes(node 1 --> query and kv, node 2 --> index and node 3 --> index)
2. Have a bucket with one scope and 5 collections. Let each collection have 10k docs
3. Create 10 indexes per collection.
4. Trigger a swap rebalance

namespace : ['test_bucket.test_scope_1.test_collection_5', 'test_bucket.test_scope_1.test_collection_4']

Logs -
https://cb-engineering.s3.amazonaws.com/yash-test/collectinfo-2023-07-29T214320-ns_1%40192.168.64.26.zip
https://cb-engineering.s3.amazonaws.com/yash-test/collectinfo-2023-07-29T214320-ns_1%40192.168.64.28.zip
https://cb-engineering.s3.amazonaws.com/yash-test/collectinfo-2023-07-29T214320-ns_1%40192.168.64.29.zip
CC -> Hemant Rajput Deepkaran Salooja