chore: use native addAbortListener

[trivikr]

This relates to...

https://nodejs.org/api/events.html#eventsaddabortlistenersignal-listener

Rationale

Node now provides a native events.addAbortListener() for real AbortSignal instances

This change switches the internal AbortSignal paths over to the native helper while preserving Undici's existing fallback behavior for EventEmitter-style signals.

Changes

• use node:events' native addAbortListener() in BodyReadable.dump() and WebSocketStream
• update lib/core/util.addAbortListener() to delegate to the native helper for AbortSignal instances while keeping the existing addEventListener/once fallback paths

Features

N/A

Bug Fixes

N/A

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.93%. Comparing base (8cfb762) to head (de15b4e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5021   +/-   ##
=======================================
  Coverage   92.92%   92.93%           
=======================================
  Files         110      110           
  Lines       35740    35747    +7     
=======================================
+ Hits        33213    33220    +7     
  Misses       2527     2527           

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[mcollina]

lgtm