Do not use findAllComponents with ref in `ee/spec/frontend/vulnerabilities/history_entry_spec.js`

When using a ref within findAllComponents() function of vue test utils it will fail because it's not supported anymore in Vue test utils v2, see warning in docs for findAllComponents.

Use another way of finding the components, e.g. defining data-testid in the component and using findAllByTestId in the spec.