Expose VSC SourceVolumeMode

[msfrucht]

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Please add a summary of your change

Copies the VolumeSnapshotContent SourceVolumeMode during DataUpload. Recent versions of the snapshot-controller do not allow the field to be changed from "Filesystem" or "Block" to nil resulting in a failure to move the VolumeSnapshot into the local namespace.

This was found in Kubernetes 1.29/OpenShift 4.16

@shubham-pampattiwar identified the underlying source of the behavior changes to https://kubernetes.io/blog/2024/04/30/prevent-unauthorized-volume-mode-conversion-ga/ and shows up in external-provisioner v4.0.0 and external-snapshotter v7.0.0.

This field is typically nil to begin with in other environments which doesn't trigger this error.

Does your change fix a particular issue?

#8259

Fixes #(issue)

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.21%. Comparing base (42de654) to head (7580538).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8261   +/-   ##
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  Coverage   59.21%   59.21%           
=======================================
  Files         367      367           
  Lines       30841    30842    +1     
=======================================
+ Hits        18262    18263    +1     
  Misses      11119    11119           
  Partials     1460     1460           

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[Lyndon-Li]

@msfrucht Please help to cherry-pick this PR to 1.14 branch.