[VMOwnedVolumes][Draft] Completion gaps- UnregisterVolumeEx and additional tests

[deepakkinni]

What this PR does / why we need it:

Critical Functional Gap

The greenfield attach path uses UnregisterVolume (old single-phase API) instead of UnregisterVolumeEx (new two-phase API with PENDING_UNREGISTER + ACK). The spec (Section 7.3, A.3/A.4) requires the two-phase commit model where:

• A.3: CnsUnregisterVolumeEx marks the CNS DB row as PENDING_UNREGISTER, preserving backingDiskPath and diskUUID in the row, and returns them to CSI.
• A.4: After CVI patch and BA status write, CSI calls AckUnregister(volumeID) to delete the PENDING_UNREGISTER row.
• On crash between A.3 and A.4, the PENDING_UNREGISTER row survives, enabling crash recovery via QueryPendingUnregisters.

Currently in vm_owned_attach.go line 85, the code calls volumeManager.UnregisterVolume(ctx, volumeID, true) which:

• Does NOT return backingDiskPath/diskUUID from the unregister result (returns only a fault type string)
• Does NOT persist a PENDING_UNREGISTER row -- the CNS DB row is deleted immediately
• Does NOT require an ACK step
• Breaks the crash recovery model in Section 14.2

The govmomi fork already has UnregisterVolumeEx, AcknowledgeUnregister, and QueryPendingUnregisters client methods. The CSI driver's Manager interface already has QueryPendingUnregisters and AckUnregister wrappers. What is missing is:

1. An UnregisterVolumeEx method on the Manager interface that returns (backingDiskPath, diskUUID, error)
2. Wiring the attach path to use it instead of the old UnregisterVolume
3. Adding the ACK step after CVI patch + BA status write

Test Coverage Gaps

Multiple areas lack unit tests:

• PV-bind reconciler (cvi_pv_bind.go) -- no tests for ownerRef patching, crash recovery, cross-namespace rebind
• MaybeLazilyCreateCVI end-to-end flow -- no test
• VMHasVCenterSnapshots helper -- no test
• ReregisterVolumeAsFCD -- no unit tests
• reconcileSnapshotDeletion / processDiskAfterSnapshotDeletion -- no unit tests
• GetRetainedDiskUUIDs / IsVolumeRetainedByVCenterSnapshot -- no unit tests
• Full sync CVI filter -- no dedicated unit test (only mock stubs)
• checkCVISnapshotRetained admission webhook -- no dedicated named test case
• reconcileStaleCVIs -- limited test coverage (only noop paths tested)

Minor Issues

• Commit 9e2bb78e includes an unrelated .cursor/rules/pith.mdc file that should be excluded

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:
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If jtest is used to trigger precheckin tests, paste the result after jtest completes and remove [WIP] in the PR subject.
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Release note:

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: deepakkinni

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[k8s-ci-robot]

PR needs rebase.

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[k8s-ci-robot]

@deepakkinni: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-vsphere-csi-driver-verify-vet	bcd4696	link	true	/test pull-vsphere-csi-driver-verify-vet
pull-vsphere-csi-driver-verify-golangci-lint	bcd4696	link	true	/test pull-vsphere-csi-driver-verify-golangci-lint
pull-vsphere-csi-driver-verify-fmt	bcd4696	link	true	/test pull-vsphere-csi-driver-verify-fmt
pull-vsphere-csi-driver-build	bcd4696	link	true	/test pull-vsphere-csi-driver-build
pull-vsphere-csi-driver-unit-test	bcd4696	link	true	/test pull-vsphere-csi-driver-unit-test
pull-vsphere-csi-driver-verify-staticcheck	bcd4696	link	true	/test pull-vsphere-csi-driver-verify-staticcheck
pull-vsphere-csi-driver-verify-shell	bcd4696	link	true	/test pull-vsphere-csi-driver-verify-shell

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.

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