Update "jest vue3 mr" jobs to not ignore quarantined files that have been changed

This is would be one of the final ways to strongly encourage more compatibility with Vue 3 in our Jest test suite.

#498926 (closed) made sure that we don't regress in Vue 3 compatibility in tests.

The jest vue3 mr jobs currently do not run quarantined specs under Vue 3. Let's make it stricter such that if a user touches a spec that's quarantined, the spec is run. This means even if the author didn't break it, they have to fix it.

There will be circumstances where that's impractical, so we'll provide an escape hatch: apply a ~pipeline:allow-vue3-failure (or similar) label to the merge request.