Shorten the GKE cluster name

[saikat-royc]

Some intree tests create disks with names which is a combination of
cluster name + UUID, and exceeds the 63 chars limit of disk resources

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
Fix in-tree tests run on GKE clusters

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:
For reference of how the pd name is created: https://github.com/kubernetes/kubernetes/blob/master/test/e2e/framework/providers/gce/gce.go#L208
Without this fix, the disk resource name is something like this gke-gcp-pd-csi-driver-test-cluster-8ac691ac-4d1f-41ed-9d6c-e528d0101609 which results in error Invalid value for field 'resource.name': 'gke-gcp-pd-csi-driver-test-cluster-8ac691ac-4d1f-41ed-9d6c-e528d0101609'. Must be a match of regex '(?:[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?)'
Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: saikat-royc

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[saikat-royc]

/assign @verult

[verult]

/lgtm