next.js

7c10fcf2 - Ensure we copy map file as well for experimental tracing (#68676)

Ensure we copy map file as well for experimental tracing (#68676) These files can be present if server source maps flag is enabled so need copying as well. Also removes incorrect `_not-found` special case which will need revisiting and updating define-env check to not apply in dev. x-ref: [slack thread](https://vercel.slack.com/archives/C056QDZARTM/p1723119830912809)