The new ProductAggregatesCard child component calls useI18n() during
setup. The existing invoicing-period-queue-state.behavior.spec.js
mounts the parent InvoicingBillingPeriodViewAll view without providing
a vue-i18n instance, which causes the Serial unit suite to fail with:
SyntaxError: Need to install with `app.use` function
Wire createTestI18n() into the mount() global plugins so the new card
and any other future i18n-using children render correctly in this
serial spec.
