test(node): Fix flaky negative sampling (static) envelope ordering

[github-actions]

The negative sampling (static) integration test (suites/tracing/sampling-static/test.ts) intermittently failed on CI with an envelope-ordering assertion error.

Root cause

The test used ordered envelope matching, expecting the GET /ok transaction to arrive before the client_report that records the negatively-sampled /health sample_rate outcome. These two envelopes originate from independent flush mechanisms:

• The GET /ok transaction is transmitted as soon as its root span ends.
• The discarded /health outcome only leaves the SDK via the client report flushed on clientReportFlushInterval (1000ms).

Because the flush timings are independent, their relative arrival order is racy. When the client-report interval fires after the /health outcome is recorded but before the /ok transaction is transmitted, the client_report arrives first and the ordered matcher throws Expected envelope item type 'transaction' but got 'client_report'.

Fix

Add .unordered() so envelope arrival order no longer matters. Both assertions (the transaction and the client_report) are still required to arrive and are checked exactly as before — only the strict sequencing is relaxed. This mirrors the pattern already used in tracing/postgresjs, tracing/apollo-graphql, and express/handle-error.

Fixes #21990