Recovering databases with purges not replicated after nodes in maintenance_mode

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## Description

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I have a cluster with 6 nodes, with big databases (> 220M documents).
Each database lives with many creations, updates and purges (no deletion). Exceptionnaly, I set my nodes in maintenance_mode for a long time (16h) and discovered that purges were not replicated in nodes with maintenance_mode to true.
After a quick search, I found this issue (https://github.com/apache/couchdb/issues/2139) which correspond to my anomaly.

I've upgraded a test environment to v3.3.2 and the anomaly is well corrected for **new** purges. But is there a way to recover **old** purges and how should I do it ?

Thanks for your support.

## Steps to Reproduce

[NOTE]: # ( Include commands to reproduce, if possible. curl is preferred. )
- Put a node in maintenance mode
- Purge a document
- Put back the node from maintenance mode
- Migrate to 3.3.2
- The purge is still not replicated

## Expected Behaviour

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Documents purged are purged in every node.

## Your Environment

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* CouchDB version used: 3.2.3
* Browser name and version: not relevant
* Operating system and version: Ubuntu 18.04

## Additional Context

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Read the linked issue #2139 and the CouchDB 3.3.2 changes addressing purge replication first. The report gives a six-node maintenance-mode scenario but does not identify a recovery command, relevant source files, or tests. Determine whether old purges can be recovered and document or test the supported approach; the issue provides no specific entry point to start from.

Written by the indexing model from the issue text.