remove CSIMigrationvSphereComplete flag

[divyenpatel]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This is follow-up PR after #98243 to remove deprecated flagCSIMigrationvSphereComplete.

Which issue(s) this PR fixes:

Fixes #96730

Special notes for your reviewer:

Testing is in progress

Does this PR introduce a user-facing change?

NONE

remove CSIMigrationvSphereComplete flag 

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

/sig storage
/assign @msau42 @Jiawei0227

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: divyenpatel
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[k8s-ci-robot]

@divyenpatel: The following tests failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-kubernetes-verify	da2e99f	link	/test pull-kubernetes-verify
pull-kubernetes-e2e-gce-storage-slow	da2e99f	link	/test pull-kubernetes-e2e-gce-storage-slow

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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. I understand the commands that are listed here.

[Jiawei0227]

ohh I had the exact same change here: #101272

[divyenpatel]

Thanks, @Jiawei0227, I am closing this PR.

[caesarxuchao]

/triage accepted