test: fix flaky test-http2-close-while-writing

[mcollina]

Summary

Fixes flaky test test/parallel/test-http2-close-while-writing.js which was timing out on macOS.

Problem

The test uses stream.on('data', ...) which can fire multiple times when receiving the 64KB data chunk sent by the client. Each data event triggers client_stream.destroy() via process.nextTick(), leading to multiple destroy calls and intermittent timeouts.

Solution

Changed stream.on('data', ...) to stream.once('data', ...) to ensure the callback only fires once, regardless of how many data chunks arrive. This pattern is consistent with similar tests like test-http2-many-writes-and-destroy.js.

Verification

Verified with python3 tools/test.py --repeat 100 without failures.

Refs: nodejs/reliability#1459

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.74%. Comparing base (3819c7f) to head (c0acd73).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61764      +/-   ##
==========================================
- Coverage   89.74%   89.74%   -0.01%     
==========================================
  Files         675      675              
  Lines      204642   204642              
  Branches    39322    39320       -2     
==========================================
- Hits       183657   183647      -10     
- Misses      13257    13283      +26     
+ Partials     7728     7712      -16     

see 48 files with indirect coverage changes

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[lpinca]

See #58252, there is a deeper issue.