[release-7.0]: Fix detecting default annotation on VolumeGroupSnapshotClass

[Madhu-1]

The IsDefaultAnnotation() function has been extended to check for the correct default annotation, taking the Kind of the object into consideration.

(cherry picked from commit aa837d1)

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/kind api-change
/kind bug
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What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Cherry-pick from PR [#1015](https://github.com/kubernetes-csi/external-snapshotter/pull/1015) Adding the annotation `groupsnapshot.storage.kubernetes.io/is-default-class=true` on a VolumeGroupSnapshotClass will cause that VolumeGroupSnapshotClass to be used by default.

[Madhu-1]

/assign @xing-yang

[k8s-ci-robot]

Hi @Madhu-1. Thanks for your PR.

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[xing-yang]

/ok-to-test

[xing-yang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Madhu-1, xing-yang

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