[windows] Disk Write Queue doesn't drain completely after rebalancing out nodes from the cluster

Disk Write Queue doesn't drain completely after rebalancing out some nodes from the cluster

Test to reproduce:
./testrunner -i vm-4win.ini -t rebalance.rebalanceout.RebalanceOutTests.incremental_rebalance_out_with_ops,replicas=2,items=100000,max_verify=100000,doc_ops=create

The test creates a 7 node cluster and then keeps rebalancing out 2 nodes at a time while data loading is in progress.

After rebalance is done, one of the nodes in the cluster has ep_queue_size=1 and doesn't drain for > 150 seconds.

Please see attached screenshot, all data activity is finished and compaction also completed, but DWQ is still 1.

Reproducible on both internal VMs and EC2 consistently.

Diagnostics are attached.