Automatic merge from submit-queue (batch tested with PRs 57552, 57994). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Fix vm cache in concurrent case in azure_util.go
**What this PR does / why we need it**:
Fix a bug in azure vm cache. In case two callers call 'getVirtualMachine', if the second caller sees non-empty request.VM, it should return that value, instead of the default 'vm' variable.
**Which issue(s) this PR fixes**
Follow up of #57031
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
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