fix: fix update run name CEL

[britaniar]

Description of your changes

I have:

• Updated the CEL validation for the update run name. The name cannot be longer than 63 characters.

• Run make reviewable to ensure this PR is ready for review.

How has this code been tested

• Manually
• Integration test

Special notes for your reviewer

Create a clusterStagedUpdateRun with the max characters allowed which is 127 based on the CEL check. When the controller tried to create the cluster approval request I got this error:

"Failed to create the approval request" err="ClusterApprovalRequest.placement.kubernetes-fleet.io .... is invalid: metadata.labels: Invalid value: \"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\": must be no more than 63 characters" 

Seems like the cap for the update run name should be 63 characters not 127 so that it fits in the label.

kubefleet/pkg/controllers/updaterun/execution.go

Line 632 in 6f3e972

placementv1beta1.TargetUpdateRunLabel: updateRunName,

Label Values need to be <= 63 characters (https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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