FTS indexing stuck at 95.14%

Build 7.0.0 build 1655

Steps to reproduce. This is not consistent but found this issue when working the below steps.

1. Cluster with kv,kv,kv,kv,search,search
2. Create default bucket
3. Create default index with 2 fields
4. Load bucket with 100M docs each of size 50B
5. Let index complete
6. Now start loading another 200M new docs while mutating 100M docs loaded before.
7. And in parallel run index defn update, updating replica count to 0, sleep 5mins and update it back to 1
8. And when the indexing is at around 55%. Stopped the above step.
9. Index was not completed even after 2 days, instead it was stuck at 95.14%.

Logs:

https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.121.195.zip
https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.121.249.zip
https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.122.185.zip
https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.122.187.zip
https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.122.188.zip
https://cb-jira.s3.us-east-2.amazonaws.com/logs/index-stuck/collectinfo-2020-03-30T021332-ns_1%40172.23.122.190.zip

In this instance, step 7 was stopped at 2020-03-27T18:34:59. Index was stuck at 95.14% even after 2 days : Sun Mar 29 19:38:51 PDT 2020.