Reset VolumeSnapshotRef in Backup Sync Flow

[anshulahuja98]

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Please add a summary of your change

Follow on fix to #7924
Fixes: #7978

Does your change fix a particular issue?

Fixes #(issue)

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file or added /kind changelog-not-required as a comment on this pull request.
• Updated the corresponding documentation in site/content/docs/main.

[anshulahuja98]

/kind changelog-not-required

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 58.82%. Comparing base (d1d331f) to head (4a6a362).
Report is 22 commits behind head on main.

Files	Patch %	Lines
pkg/controller/backup_sync_controller.go	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7983      +/-   ##
==========================================
+ Coverage   58.77%   58.82%   +0.05%     
==========================================
  Files         345      346       +1     
  Lines       28768    28854      +86     
==========================================
+ Hits        16908    16973      +65     
- Misses      10430    10449      +19     
- Partials     1430     1432       +2     

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[kaovilai]

Is this snapshot namespacedname supposed to be non-existing?
Can the string here be anything?

[anshulahuja98]

@kaovilai this is a copy paste from -https://github.com/vmware-tanzu/velero/blame/824bebbad7bc61077c6e80731468fb020d3dfd4f/pkg/util/csi/volume_snapshot.go#L641

My understanidng is that any name should work here.
We are creating a static VSC

[kaovilai]

1.14 cherry-pick: #8003