Next.js Data Quality

[stephanie-anderson]

This is the epic issue for all things we wanna improve around the Next.js SDK data quality.

GitHub Project Board:
https://github.com/orgs/getsentry/projects/169/views/17?sliceBy%5Bvalue%5D=SDK+Data+Quality

### Tasks
- [ ] https://github.com/getsentry/sentry-javascript/issues/7450
- [ ] https://github.com/getsentry/sentry-javascript/issues/6804
- [ ] https://github.com/getsentry/sentry-javascript/issues/9568
- [ ] https://github.com/getsentry/sentry-javascript/issues/7925