Next.js: Pick up `clientTraceMetadata` in pages router instrumentation

[lforst]

Description

vercel/next.js#69620 is merged and we can pick up the meta tags in the pages router.

Ref: #8105

[lforst]

Ok, we need to switch all the pages router instrumentation to OTEL for this to work, because as of now, our traces and the nextjs traces are completely separate, and we are getting a different trace id from nextjs than we do emit ourselves.

This task basically depends on #13737

[lforst]

Will automagically fix-itself with #13889

PR to test #14059

[github-actions]

A PR closing this issue has just been released 🚀

This issue was referenced by PR #13889, which was included in the 8.36.0 release.