In Next 12, `router.replace()` treats the page props cache as authoritative when fetching SSG props in preview mode. This makes sense outside preview mode (static props won't change), but within preview mode this prevents reloading the preview data dynamically without force-refreshing the page.

This PR fixes the problem by instructing Next to bypass the props cache not only if it's an SSG route, but also only if preview mode is off.

Repro: https://github.com/kamsar/next-replace-previewmode-staticprops/blob/main/pages/index.js