Migrate to Vitest

[aaemnnosttv]

Feature Description

Once #10094 is completed, our dependencies for JS tests will no longer be restricted to our current version of Node JS and so we can migrate to Vitest – a modern Jest compatible testing framework with much better performance and support.

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Acceptance criteria

• Vitest should be used as the test runner for JS tests – specifically those run by the current tests:js script
• A best effort should be made to minimize changes necessary to accomplish the migration (see https://vitest.dev/guide/migration.html#jest)
  • Changes that require substantial effort or changes affecting a large number of files that aren't required for the initial change should be opened as follow-up issues

Implementation Brief

Test Coverage

QA Brief

Changelog entry

[benbowler]

Note, we can create a follow up ticket to migrate the E2E tests as well because these use jest to run as well.

[aaemnnosttv]

@benbowler that's the plan, at least once we confirm that we can do that with this issue 😄