4.0.x, by @Ayanda-D: stop QQ replicas when a QQ is forced to shrink to a single replica #12475
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This is #12427 by @Ayanda-D submitted against
v4.0.x.Shrinking operations did not stop QQ replicas. This was easy to miss because QQs are usually shrunk before a node is removed from the cluster.
However, there is a scenario where this is not the case. If some nodes (replicas) need to be replaced, in particular when a majority of nodes cannot be recovered for any reasons, the recovery process will involve shrinking a QQ to just one member so that it has an online quorum (of 1 node out of 1) before new replicas can be added.
For this to succeed, the older replicas must be stopped and deleted from the (QQ) cluster.