Disable streaming SSR for `pages`, preferring the static rendering. This
was leftover from when we implemented the server components alpha on
`pages` and causes issues for people upgrading from Next.js 12 to 13
when the `chunked` response is unexpected, e.g. with certain CDN setups.
Streaming is the default in `app` and that has the right implementation
to fully leverage streaming in React including when navigating
client-side as the router is built around React transitions.
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