fix: validate EOF for chunked h1 responses

[mcollina]

This relates to...

Backport of #5273 to v7.x.

Rationale

This brings the HTTP/1.1 EOF validation fix for truncated chunked responses to the v7.x line.

Changes

• call parser.finish() on EOF / close paths instead of treating the response as complete
• surface protocol errors for truncated chunked responses
• add regression coverage for both Client and fetch

Features

N/A

Bug Fixes

• reject truncated chunked HTTP/1.1 responses terminated by EOF

Breaking Changes and Deprecations

None

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

❌ Patch coverage is 86.44068% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.89%. Comparing base (301f347) to head (35efd5e).

Files with missing lines	Patch %	Lines
lib/dispatcher/client-h1.js	86.44%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             v7.x    #5307   +/-   ##
=======================================
  Coverage   92.88%   92.89%           
=======================================
  Files         112      112           
  Lines       35785    35828   +43     
=======================================
+ Hits        33239    33281   +42     
- Misses       2546     2547    +1     

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