ref(nextjs): Make Pages Router API Routes instrumentation OTEL ready

[lforst]

Drop all spans/transactions emitted by Next.js for pages router API routes because they are currently super buggy with wrong timestamps. Fix pending: vercel/next.js#70908

This is just a bit of prep-work so we can at some point disable the logic where we turn on all Next.js spans and still have high quality data.

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	22.73 KB	added	added
@sentry/browser - with treeshaking flags	21.53 KB	added	added
@sentry/browser (incl. Tracing)	34.97 KB	added	added
@sentry/browser (incl. Tracing, Replay)	71.5 KB	added	added
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	61.91 KB	added	added
@sentry/browser (incl. Tracing, Replay with Canvas)	75.82 KB	added	added
@sentry/browser (incl. Tracing, Replay, Feedback)	88.59 KB	added	added
@sentry/browser (incl. Tracing, Replay, Feedback, metrics)	90.46 KB	added	added
@sentry/browser (incl. metrics)	27 KB	added	added
@sentry/browser (incl. Feedback)	39.87 KB	added	added
@sentry/browser (incl. sendFeedback)	27.38 KB	added	added
@sentry/browser (incl. FeedbackAsync)	32.17 KB	added	added
@sentry/react	25.49 KB	added	added
@sentry/react (incl. Tracing)	37.94 KB	added	added
@sentry/vue	26.9 KB	added	added
@sentry/vue (incl. Tracing)	36.86 KB	added	added
@sentry/svelte	22.87 KB	added	added
CDN Bundle	24.05 KB	added	added
CDN Bundle (incl. Tracing)	36.76 KB	added	added
CDN Bundle (incl. Tracing, Replay)	71.24 KB	added	added
CDN Bundle (incl. Tracing, Replay, Feedback)	76.55 KB	added	added
CDN Bundle - uncompressed	70.53 KB	added	added
CDN Bundle (incl. Tracing) - uncompressed	109.04 KB	added	added
CDN Bundle (incl. Tracing, Replay) - uncompressed	220.93 KB	added	added
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	234.15 KB	added	added
@sentry/nextjs (client)	37.91 KB	added	added
@sentry/sveltekit (client)	35.56 KB	added	added
@sentry/node	125.03 KB	added	added
@sentry/node - without tracing	93.48 KB	added	added
@sentry/aws-serverless	103.17 KB	added	added