add check continue VGS deletion

[yati1998]

this commit adds check to continue deleting the volumegroupsnapshot in case there are no snapshotcontent found under that group.

https://github.com/kubernetes-csi/external-snapshotter/issues/1035

[k8s-ci-robot]

Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: yati1998 Once this PR has been reviewed and has the lgtm label, please assign jingxu97 for approval. For more information see the Kubernetes Code Review Process.

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[k8s-ci-robot]

Hi @yati1998. Thanks for your PR.

I'm waiting for a kubernetes-csi 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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Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[yati1998]

@Madhu-1 @xing-yang please take a look. I tested the changes and now the volumegroupdeletion is not getting stuck even after multiple deletions

[xing-yang]

/ok-to-test

[xing-yang]

@yati1998 Is there an issue opened for this bug fix? If there is one, please add to your PR description.