feat: Always stream INP and remove standalone v1 spans

MIGRATION.md

@@ -336,6 +336,7 @@ Sentry.init({
 ### `@sentry/browser`
 
 - The experimental `_experiments.enableStandaloneClsSpans` and `_experiments.enableStandaloneLcpSpans` options were removed from both `browserTracingIntegration` and `webVitalsIntegration`. CLS and LCP are no longer configurable: they are recorded as measurements on the pageload span, unless span streaming is enabled (`traceLifecycle: 'stream'`), in which case they are sent as dedicated spans.
+- INP is now always sent as a web vital span (streamed when span streaming is enabled, standalone otherwise) that carries its value as a `browser.web_vital.inp.value` attribute. Previously, with span streaming disabled, INP was sent as a standalone span that carried its value as a span measurement.
 
 ### `@sentry/node` / Server-side SDKs