[Flaky CI]: E2E nextjs-16-cf-workers Test - tests/prefetch-spans.test.ts › Prefetch client spans should have a http.request.prefetch attribute

### Flakiness Type

Other / Unknown

### Name of Job

E2E nextjs-16-cf-workers Test

### Name of Test

[chromium] › tests/prefetch-spans.test.ts:5:5 › Prefetch client spans should have a http.request.prefetch attribute

### Link to Test Run

https://github.com/getsentry/sentry-javascript/actions/runs/33646601039/job/100304419536

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_This issue was automatically created._

Start with tests/prefetch-spans.test.ts and reproduce the failure from the linked E2E nextjs-16-cf-workers job. Trace why the Prefetch client spans assertion intermittently lacks the http.request.prefetch attribute, then verify the test passes reliably while retaining that assertion.

Rédigé par le modèle d'indexation à partir du texte de l'issue.