Move file new tab check in new test

What does this MR do and why?

Closes #436492 (closed)

The check whether the file opens in a new tab is not dependent on the lineData so it's unnecessary to check this multiple times in the it.each. Instead, it's moved to a separate test.

MR acceptance checklist

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How to set up and validate locally

yarn jest ee/spec/frontend/security_dashboard/components/shared/vulnerability_details_graphql/index_spec.js