chore: allow testing in production env

[7nik]

Add the ability to set DEV to false for test.
It's supposed to be

if (config.production) fn = run_in_production(fn);

But due to vitest-dev/vitest#7712 unmocking doesn't work, so instead such tests are moved to the end of the queue.

This should allow adding the correct tests to #16724.

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Latest commit: 872fa3a

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[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16840