ref(browser): remove web vital standalone span experiments

MIGRATION.md

@@ -315,6 +315,10 @@ 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.
+
 ### `@sentry/node` / Server-side SDKs
 
 - `SentryContextManager` is no longer exported. It is no longer needed now that Sentry does not set up OpenTelemetry by default.