node-integration-tests: port trace semantics suites to span streaming

Follow the porting recipe in the parent issue.

Sampling, DSC, envelope headers and span linking. These suites assert on envelope headers and trace propagation rather than on instrumentation output, so they are the ones most likely to expose a real product bug rather than a test rewrite.

Suites

Envelope headers and DSC: tracing/envelope-header/* (7 dirs), tracing/dsc-txn-name-update, tracing/double-baggage/* (3 dirs), tracing/meta-tags, tracing/meta-tags-twp, tracing/meta-tags-twp-errors
Sampling: tracing/sampling-static, tracing/sample-rate-propagation/* (4 dirs), tracing/sample-rand-propagation, tracing/no-parent-span-client-report
Trace lifetime: tracing/continueTrace, tracing/startNewTrace, tracing/traceid-recycling, tracing/traceid-recycling-with-spans
Span shaping: tracing/linking, tracing/maxSpans, tracing/tracer-start-active-span-error
Public API span surface: public-api/startSpan/* (7 dirs), public-api/beforeSendSpan-static, public-api/bindScopeToEmitter, public-api/setMeasurement, public-api/scopes/*

Twins to fold back

tracing/sampling-streamed, tracing/ignoreSpans-streamed/*, public-api/beforeSendSpan-streamed, context-streamed/*, and the 6 public-api/startSpan/*-streamed dirs.

Keep static trace lifecycle coverage

This is the group that owns the guard. Keep tracing/sampling-static and public-api/beforeSendSpan-static on the static pin. Everything else moves.

JS-3610

Is anyone working on the seven tracing/envelope-header/* suites? I'd like to take that group as a separate PR.

I tried the migration locally on 7267c254. All seven pass with span-header assertions and the existing error-header checks. The sampling-propagation fixture also needs sentry-public_key in its incoming baggage, since streamed envelopes omit tracing context without it. No SDK runtime changes appear necessary.

Would that scope work for you?