ref(browser): Create standalone INP spans via startInactiveSpan

[Lms24]

builds on top of #11696 #11699

This PR refactors how we create INP spans. Previously we'd directly initialize a SentrySpan instance with the necessary properties and manually sample the span. Ironically, we heavily discourage directly initializing a Span class.

With this refactor PR, we leverage the standalone: true flag introduced in #11696. This way, we can also use the built-in sampling functionality and ensure that we only have one logic for creating standalone span envelopes. Also bundle size should decrease slightly 🤞

Adjusted the integration tests to more thoroughly test the INP span envelopes

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser	21.65 KB (0%)
@sentry/browser (incl. Tracing)	32.68 KB (-0.09% 🔽)
@sentry/browser (incl. Tracing, Replay)	68.02 KB (-0.1% 🔽)
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	61.42 KB (-0.09% 🔽)
@sentry/browser (incl. Tracing, Replay with Canvas)	72.06 KB (-0.11% 🔽)
@sentry/browser (incl. Tracing, Replay, Feedback)	84.27 KB (-0.09% 🔽)
@sentry/browser (incl. Feedback)	37.79 KB (0%)
@sentry/browser (incl. sendFeedback)	26.43 KB (0%)
@sentry/browser (incl. FeedbackAsync)	30.93 KB (0%)
@sentry/react	24.33 KB (0%)
@sentry/react (incl. Tracing)	35.64 KB (-0.06% 🔽)
@sentry/vue	25.47 KB (+0.1% 🔺)
@sentry/vue (incl. Tracing)	34.47 KB (-0.04% 🔽)
@sentry/svelte	21.77 KB (0%)
CDN Bundle	23.95 KB (0%)
CDN Bundle (incl. Tracing)	33.96 KB (-0.19% 🔽)
CDN Bundle (incl. Tracing, Replay)	67.65 KB (-0.09% 🔽)
CDN Bundle (incl. Tracing, Replay, Feedback)	83.53 KB (-0.07% 🔽)
CDN Bundle - uncompressed	70.56 KB (0%)
CDN Bundle (incl. Tracing) - uncompressed	100.88 KB (-0.12% 🔽)
CDN Bundle (incl. Tracing, Replay) - uncompressed	210.49 KB (-0.06% 🔽)
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	256.88 KB (-0.05% 🔽)
@sentry/nextjs (client)	34.86 KB (-0.06% 🔽)
@sentry/sveltekit (client)	33.24 KB (-0.06% 🔽)
@sentry/node	138.48 KB (0%)