[ui] Prevent double-open for cmd+click on vars index links

[ChefAustin]

I pretty much duplicated the fix performed in #23832 but modified it for Vars instead of Jobs.

Not a JS guy so I could be way off-base here.

[Hopefully] Resolves #24315

[ChefAustin]

@philrenaud Perhaps you could provide some guidance here on the build failures I'm encountering?

Happy to fix up whatever is busted I'm just a skosh out of my element here.

[Pictured below: Me being out of my element]

[philrenaud]

Looks good, @ChefAustin ! Thanks for submitting it.

I've nudged the Percy tests (visual diff tests / tell us if something moved when it oughtn't have) which are set not to run on forks by default. They should come back soon and if there are visual discrepancies I'll manually review them (flakes sometimes happen with the passage of time)

I'd like to ask that you make a changelog entry for this PR — you can run make cl from the nomad directory and it should guide you through it.

[ChefAustin]

Looks good, @ChefAustin ! Thanks for submitting it.

I've nudged the Percy tests (visual diff tests / tell us if something moved when it oughtn't have) which are set not to run on forks by default. They should come back soon and if there are visual discrepancies I'll manually review them (flakes sometimes happen with the passage of time)

I'd like to ask that you make a changelog entry for this PR — you can run make cl from the nomad directory and it should guide you through it.

Thanks, @philrenaud! Changelog entry has been added in bbb1d9c.

[philrenaud]

Nice work, and thank you for the PR!