Fix AAD pod identity integration for sovereign clouds

[CecileRobertMichon]

What type of PR is this?
/kind bug

What this PR does / why we need it: AAD pod identity AzureIdentitySpec ADEndpoint and ADResourceID weren't being set which was causing it to default to AzurePublicCloud values. Setting those values so it works across all clouds.

k get azurecluster -o wide
NAME           CLUSTER        READY   REASON   MESSAGE   RESOURCE GROUP   SUBSCRIPTIONID   LOCATION     ENDPOINT
cecile-25545   cecile-25545   True                       cecile-25545     redacted         chinaeast2   cecile-25545-2b5a47a7.chinaeast2.cloudapp.chinacloudapi.cn

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1843

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Fix AAD pod identity integration for sovereign clouds

[jsturtevant]

lgtm, one point to consider on tests adding a test

[devigned]

/lgtm
/approve

... Nice work! Resuming holiday time.

[k8s-ci-robot]

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[CecileRobertMichon]

/retest

vmss flake

[CecileRobertMichon]

/cherry-pick release-1.0

[k8s-infra-cherrypick-robot]

@CecileRobertMichon: once the present PR merges, I will cherry-pick it on top of release-1.0 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.0

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[k8s-infra-cherrypick-robot]

@CecileRobertMichon: new pull request created: #1887

In response to this:

/cherry-pick release-1.0

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.