Automatic merge from submit-queue

Azure: Allow VNet to be in a separate Resource Group

**What this PR does / why we need it**: 

This PR allows Kubernetes in an Azure context to use a VNet which is not in the same Resource Group as Kubernetes.

We need this because currently Azure Cloud Provider driver assumes that it should have a VNet for himself but if there is one thing that should be shared amongst Azure resources it's a VNet cause, well, things might want to talk to each other in a private network, don't you think ?

I guess this should we backported down to 1.6 branch.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: 

fixes #49577

**Release note**:

```release-note
NONE
```

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