Description of problem: With 2 Windows nodes created by one machineset, replacing the private key will delete both the 2 Windows nodes at the beginning and then recreate them,it doesn’t follow maxUnhealthyCount rule, this will cause service breaking.

$ oc logs -f deployment.apps/windows-machine-config-operator -n openshift-windows-machine-config-operator
...
{"level":"info","ts":1634569171.675713,"logger":"controller.windowsmachine","msg":"deleting machine","machine":"openshift-machine-api/winworker-hwgqc"}
{"level":"info","ts":1634569171.685051,"logger":"controller.secret","msg":"updating secret","secret":"openshift-windows-machine-config-operator/cloud-private-key","name":"windows-user-data"}
{"level":"info","ts":1634569171.7818367,"logger":"controller.windowsmachine","msg":"unhealthy machine count for machineset","name":"winworker","total":2,"unhealthy":0}
{"level":"info","ts":1634569171.7961621,"logger":"controller.windowsmachine","msg":"machine has been remediated by deletion","name":"winworker-hwgqc"}
{"level":"info","ts":1634569171.7965193,"logger":"controller.windowsmachine","msg":"deleting machine","machine":"openshift-machine-api/winworker-nch44"}
{"level":"info","ts":1634569171.8028684,"logger":"controller.windowsmachine","msg":"unhealthy machine count for machineset","name":"winworker","total":2,"unhealthy":0}
{"level":"info","ts":1634569171.8165264,"logger":"controller.windowsmachine","msg":"machine has been remediated by deletion","name":"winworker-nch44"}
{"level":"info","ts":1634569183.5262113,"logger":"metrics","msg":"Prometheus configured","endpoints":"windows-exporter","port":9182,"name":"metrics"}
{"level":"info","ts":1634569186.2801213,"logger":"metrics","msg":"Prometheus configured","endpoints":"windows-exporter","port":9182,"name":"metrics"}
{"level":"info","ts":1634569278.3233094,"logger":"controller.windowsmachine","msg":"processing","machine":"openshift-machine-api/winworker-r7nvc","address":"172.31.249.29"}
...

Version-Release number of selected component (if applicable):
OCP version: 4.9.0-0.nightly-2021-10-16-173626
WMCO version: 4.0.0+7991f6f0

How reproducible:
Always

Steps to Reproduce:
1, Scale up 2 Windows nodes by one machineset
2, Replace private key, e.g. change openshift-qe.pem to openshift-dev.pem
3, Check WMCO log

Actual results:
both the 2 Windows nodes are deleted at the beginning and recreated

Expected results:
The 2 Windows nodes should be deleted one by one following maxUnhealthyCount rule

Additional info: