Turbopack: less eager manifest generation (#83736)
Before:
<img width="2560" height="1224" alt="Bildschirmfoto 2025-09-12 um 18 47 11" src="https://github.com/user-attachments/assets/c40d2be6-f570-40b4-8a82-7b181f2de073" />
After:
<img width="2560" height="1323" alt="Bildschirmfoto 2025-09-12 um 19 15 35" src="https://github.com/user-attachments/assets/b58826c4-88f0-4efb-b70a-fd384785af21" />
Not that drastic of a difference, because this is still a problem:
<img width="972" height="826" alt="Bildschirmfoto 2025-09-12 um 19 15 41" src="https://github.com/user-attachments/assets/5bd63a13-27ba-468c-a0a4-e66639bc47a3" />
Technically, when calling `::reference()`, there is no need to compute the path, but `ChunkData` does that on initialization.
`NEXT_TURBOPACK_TRACING=turbo-tasks pnpm next build --turbo test/production/pages-dir/production/fixture`
