- Fix ESLint errors
- Update gitlab.pot translations
- Use optional chaining
- Make template prettier
- Extract `find` helper in specs
- [Use refs][1] instead of legacy `js-` classes for component testing

And last but not least: import used `expand-button` component.

It turns out the original creation of this component wasn't perfect,
done in 18d13bf7, as it didn't bring
over the `expand-button` component from the parent modal from which it
was extracted.

Still, this went unnoticed for around 10 months, so I'm not convinced
`instances` are often - or ever - present in vulnerabilities/findings.

The snapshot test has been updated to include it as well.

[1]: https://docs.gitlab.com/ce/development/testing_guide/frontend_testing.html#how-to-query-dom-elements