stream: fix pipeline function tail deadlock

[dayun6530]

Fixes: #40685

When the final pipeline entry is a function, pipelineImpl() creates an
internal PassThrough proxy. In the promise-based pipeline API, that proxy
is not exposed to the user, so its readable side can remain unconsumed.

Once the proxy buffer reaches its high water mark, backpressure prevents
the pipeline from completing and the returned promise never resolves.

Resume the internal proxy when the final pipeline entry is a function.
This also handles the array form of pipeline() while preserving the
existing behavior for user-provided destination streams.

Tests:

• ./node test/parallel/test-stream-pipeline.js
• make lint

[nodejs-github-bot]

Review requested:

• @nodejs/streams

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.07%. Comparing base (7b6b21a) to head (90231b2).
⚠️ Report is 30 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65559      +/-   ##
==========================================
+ Coverage   90.05%   90.07%   +0.01%     
==========================================
  Files         751      751              
  Lines      254420   254430      +10     
  Branches    47975    47981       +6     
==========================================
+ Hits       229121   229169      +48     
+ Misses      16483    16437      -46     
- Partials     8816     8824       +8     

Files with missing lines	Coverage Δ
lib/stream/promises.js	100.00% <100.00%> (ø)

... and 34 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/76577/