Inject `<html data-dpl-id>` and don't inline it into JS anymore (#88761)
We don't inline `process.env.NEXT_DEPLOYMENT_ID` anymore into browser chunks, and instead read it from `<html data-dpl-id` attribute at runtime.
Closes PACK-6538
- [x] ~~Causes a hydration error at the moment.~~ Solved by removing the attribute immediately before hydration happens
<img width="1443" height="620" alt="Bildschirmfoto 2026-01-20 um 12 32 06" src="https://github.com/user-attachments/assets/b69b3a0b-129d-44f4-84d1-10572b650437" />