Update Reviews blocks tests so they catch errors with the API

[Aljullu]

Our e2e tests for the Reviews blocks didn't catch woocommerce/woocommerce-blocks#11912. That's because they test for selectors like .wc-block-review-list .wc-block-review-list-item__item:not(.is-loading) to verify the block rendered properly in the editor, but an element matching that selector is rendered even if the Rest API returns an error.

Ideally, our tests should check that the block finished loading and is showing a real review, so instead of checking for a selector, they should probably check for the review text to be displayed.

We could also take the chance to rewrite the tests in Playwright.

[Aljullu]

We should also improve the tests so they catch issues with the Order by <select>. See: woocommerce/woocommerce-blocks#11917.