Validate vCenter username and crash CSI driver if username is not a fully qualified domain name

[vdkotkar]

What this PR does / why we need it:
Cherry picking changes from #2490 and #2595 to release-2.6 branch.

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

Testing done:
Will run e2e tests

Special notes for your reviewer:

Release note:

Validate vCenter username and crash CSI driver if username is not a fully qualified domain name

[k8s-ci-robot]

Hi @vdkotkar. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[chethanv28]

/ok-to-test
/approve

[divyenpatel]

@vdkotkar can you update testing done section so we can merge this PR?

[svcbot-qecnsdp]

Started vanilla Block pipeline... Build Number: 2265

[svcbot-qecnsdp]

Block vanilla build status: FAILURE 
Stage before exit: e2e-tests 

[svcbot-qecnsdp]

Started vanilla Block pipeline... Build Number: 2269

[svcbot-qecnsdp]

Block vanilla build status: FAILURE 
Stage before exit: e2e-tests 

[divyenpatel]

@vdkotkar can you verify test manually. Seem pipeline is failing.

[svcbot-qecnsdp]

Started vanilla Block pipeline... Build Number: 2274

[svcbot-qecnsdp]

Block vanilla build status: FAILURE 
Stage before exit: testbed-deployment 

[divyenpatel]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chethanv28, divyenpatel, vdkotkar

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• OWNERS [chethanv28,divyenpatel]

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[divyenpatel]

/lgtm