Upgrading to MB-41255

Updated MB as this issue is generic to any upgrade where we want to get a user to a release with MB-41255, this could be 6.0.4-MP2, 6.5.1 (an MP planned) or 6.6.1

Steps to Repro
Ran the following script on 6.0.4-3082.

./testrunner -i /tmp/win10-bucket-ops.ini -p  -t epengine.basic_ops.basic_ops.test_MB_32114,nodes_init=3,replicas=2,skip_cleanup=True,bucket_size=100,items=200000,active_resident_threshold=13,skip_cleanup=True

 
It reproduces MB-41255 on 6.0.4-3082.

It creates a 3 node cluster (172.23.106.89, 172.23.106.92 and 172.23.120.119).
Create a default bucket with 2 replicas.
Creates 10k docs with xattrs.
Create another 350k docs to push the default bucket into heavy dgm(10%).
Now deletes those 10k docs with delWithMeta.

So the bucket default has 350000 active docs and 720000 replica docs.

Now we try to upgrade the cluster to 6.0.4-MP2 node(by adding 172.23.120.120) and removing a 6.0.4 node(172.23.120.119) and starting swap rebalance. Rebalance hangs at 0%.

cbcollect_info attached.