http: drain server request before destroying

[dayun6530]

Refs: #49429

When a server IncomingMessage is consumed using an async iterator and
iteration terminates before the request body is fully consumed, the
IncomingMessage is destroyed while the underlying keep-alive socket
remains open.

Pending request body data can then be pushed to the destroyed stream.
push() returns false, causing the HTTP parser to pause the socket.
A subsequent request that reuses the same keep-alive socket can then stall.

This change dumps the remaining server request body before detaching and
destroying the IncomingMessage.

A regression test verifies that a subsequent request can reuse the same
keep-alive socket without timing out.

Tests:

• python3 tools/test.py --mode=release parallel/test-http-server-for-await-keepalive
• python3 tools/test.py --mode=release parallel/test-http-client-abort-keep-alive-destroy-res parallel/test-http-agent-keepalive
• python3 tools/test.py --mode=release parallel/test-stream-readable-async-iterators parallel/test-stream-pipeline-async-iterator
• make lint-js

[nodejs-github-bot]

Review requested:

• @nodejs/streams

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.05%. Comparing base (bb5cffc) to head (6d8cf43).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65674      +/-   ##
==========================================
- Coverage   90.06%   90.05%   -0.01%     
==========================================
  Files         754      754              
  Lines      255747   255748       +1     
  Branches    48318    48327       +9     
==========================================
- Hits       230327   230309      -18     
+ Misses      16550    16546       -4     
- Partials     8870     8893      +23     

Files with missing lines	Coverage Δ
lib/internal/streams/destroy.js	93.64% <100.00%> (+0.01%)	⬆️

... and 35 files with indirect coverage changes

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