feat(node)!: Remove init, preload entry points and preloadOpenTelemetry (#23074)

## What

Remove the following from `@sentry/node`, part of the v11 major:

* The `@sentry/node/init` and `@sentry/node/preload` no-code entry
points.
* The `preloadOpenTelemetry()` function.
* The `node-express-{cjs,esm}-preload` e2e apps and the `no-code`
integration suite that tested them.

Also repurposes the `express/late-init` integration suite (renamed to
`express/ignore-layers-type`) into a focused `ignoreLayersType` test.

## Why

All instrumentation is channel-based via orchestrion and is set up when
the instrumented module loads, so preloading no longer does anything.
`preloadOpenTelemetry()` could only ever preload the Sentry HTTP
breadcrumb/propagation instrument, which normal `init()` already sets
up, so it had quietly stopped doing its advertised job.

The issue proposed deprecating `init`/`preload`, but since `develop` is
the v11 line a deprecation cycle buys nothing, so these are removed
outright. `@sentry/node/import` stays as the one supported hook.
`@sentry/node/loader` and `@sentry/node/auto-diagnostic-channels` from
the issue are already moot: `/loader` was removed with the iitm cleanup,
and `/import` already is the orchestrion diagnostics-channel hook that
`/auto-diagnostic-channels` was meant to become.

The `late-init` suite existed to guard lazy Express option loading via a
later `init()`, a mechanism that now lives only in `@sentry/core`'s
`patchLayer` (Deno-only, unit-tested) and is unreachable in node under
orchestrion. It was also the only node e2e test exercising
`ignoreLayersType`, so it is kept and refocused on that option rather
than deleted.

Closes: #21483

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: andreiborza

MIGRATION.md

@@ -236,8 +236,6 @@ node --require ./instrument.js app.js
 node --import ./instrument.js app.js
 ```
 
-The same applies to the no-code entry points, e.g. `node --import=@sentry/node/init app.js` and `node --import @sentry/node/preload app.js`.
-
 ### Span streaming is now the default
 
 Affected SDKs: All SDKs.
@@ -613,6 +611,8 @@ Sentry.init({
 - The `registerEsmLoaderHooks` option was removed. All instrumentation is now channel-based (via `@sentry/server-utils`), so the SDK no longer registers `import-in-the-middle` ESM loader hooks and the option no longer had any effect.
 - The deprecated `SentryHttpInstrumentation` and `SentryNodeFetchInstrumentation` exports were removed. Use `instrumentHttpOutgoingRequests()` and the `nativeNodeFetchIntegration` respectively.
 - The `generateInstrumentOnce` export was removed (from `@sentry/node` and the framework SDKs that re-exported it). It wrapped OpenTelemetry's `registerInstrumentations` and is no longer needed now that instrumentation is channel-based.
+- The `@sentry/node/init` and `@sentry/node/preload` entry points were removed. Create your own instrument file that calls `Sentry.init()` and preload it with `node --import ./instrument.mjs app.js` instead.
+- The `preloadOpenTelemetry()` function was removed. All instrumentation is now channel-based via `orchestrion` and is set up when the instrumented module loads, so preloading is no longer needed.
 - The `@sentry/node/loader` entry point was removed. Use `node --import @sentry/node/import` instead.
 - (Astro) The `@sentry/astro/loader` entry point was removed. Use `node --import @sentry/astro/import` instead.
 - (AWS Lambda) The `@sentry/aws-serverless/loader` entry point was removed. Use `node --import @sentry/aws-serverless/import` instead.

dev-packages/e2e-tests/test-applications/node-exports-test-app/scripts/consistentExports.ts

@@ -18,7 +18,6 @@ const NODE_EXPORTS_IGNORE = [
   'setOpenTelemetryContextAsyncContextStrategy',
   'getDefaultIntegrationsWithoutPerformance',
   'initWithoutDefaultIntegrations',
-  'preloadOpenTelemetry',
   // Internal helper only needed within integrations (e.g. bunRuntimeMetricsIntegration)
   '_INTERNAL_normalizeCollectionInterval',
   // not exported by bun