[Next.js] Don't set `experimental.instrumentationHook` for Next.js >= 15

[lforst]

The hook has been stabilized and a warning will be emitted if the setting is set: vercel/next.js#68853

I spotted some env var process.env.__NEXT_VERSION in the Next.js repo. Maybe we can use that to get the version: https://github.com/lforst/nextjs-fork/blob/06c5ea4f16a1ea0eeef0c76c89154e328d6a3faa/packages/next/src/build/index.ts#L718

[lforst]

Resolved with #13586