Trace instrumentation startup (#97296)
## Summary
- trace instrumentation module loading and `register()` execution as
separate startup spans
- preserve the original timestamps when the OpenTelemetry provider is
installed by `register()` itself
- export both lifecycle spans by default without attaching them to an
unrelated request
- verify standard and direct-entrypoint startup with a collector
connected before the server starts
## Why
Loading `instrumentation.ts` and running the user-defined `register()`
hook have different owners and remediation paths. Separate spans make
startup delays attributable while preserving honest lifecycle parentage:
these spans normally occur before a request identity exists.
## Verification
- `pnpm build-all`
- `pnpm --filter=next build`
- `pnpm --filter=next types`
- `pnpm exec jest packages/next/src/server/lib/trace/tracer.test.ts
--runInBand`
- focused instrumentation-startup E2E in development and production with
Turbopack and Webpack
- Prettier, ESLint, and `git diff --check`
## Stack
Depends on **Trace route module preparation**.
