Make spec/frontend/usage_quotas/storage/components/container_registry_usage_spec.js Vue3 compatible

What does this MR do and why?

Fixes Vue3 specs on spec/frontend/usage_quotas/storage/components/container_registry_usage_spec.js

References

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• Related to #510889 (closed)

MR acceptance checklist

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Screenshots or screen recordings

N/A

How to set up and validate locally

VUE_VERSION=3 yarn jest spec/frontend/usage_quotas/storage/components/container_registry_usage_spec.js