fix: pass through respose body after process partial

[M4tteoP]

ports to upstream corazawaf/coraza-caddy#235.
cc @hnakamur

[codecov]

Codecov Report

❌ Patch coverage is 54.54545% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.24%. Comparing base (93b606a) to head (1940eca).

Files with missing lines	Patch %	Lines
http/interceptor.go	54.54%	6 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1461      +/-   ##
==========================================
- Coverage   85.27%   85.24%   -0.03%     
==========================================
  Files         173      173              
  Lines        8400     8411      +11     
==========================================
+ Hits         7163     7170       +7     
- Misses        991      993       +2     
- Partials      246      248       +2     

Flag	Coverage Δ
coraza.rule.case_sensitive_args_keys	85.20% <54.54%> (-0.03%)	⬇️
coraza.rule.mandatory_rule_id_check	85.23% <54.54%> (-0.03%)	⬇️
coraza.rule.multiphase_evaluation	84.96% <54.54%> (-0.03%)	⬇️
coraza.rule.no_regex_multiline	85.23% <54.54%> (-0.03%)	⬇️
default	85.24% <54.54%> (-0.03%)	⬇️
examples+	16.51% <ø> (ø)
examples+coraza.rule.case_sensitive_args_keys	85.13% <54.54%> (-0.03%)	⬇️
examples+coraza.rule.mandatory_rule_id_check	85.23% <54.54%> (-0.03%)	⬇️
examples+coraza.rule.multiphase_evaluation	84.75% <54.54%> (-0.03%)	⬇️
examples+coraza.rule.no_regex_multiline	85.07% <54.54%> (-0.03%)	⬇️
examples+memoize_builders	85.18% <54.54%> (-0.03%)	⬇️
examples+no_fs_access	82.82% <54.54%> (-0.03%)	⬇️
ftw	85.24% <54.54%> (-0.03%)	⬇️
memoize_builders	85.36% <54.54%> (-0.03%)	⬇️
no_fs_access	84.76% <54.54%> (-0.03%)	⬇️
tinygo	85.22% <54.54%> (-0.03%)	⬇️

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[Copilot]

Pull request overview

This PR fixes an issue where response body data was not being passed through to downstream after partial processing when the response body limit is reached with ProcessPartial action. The fix ensures that when WriteResponseBody returns fewer bytes than provided (indicating partial processing), the remaining bytes are written directly to the downstream writer.

Key changes:

• Extracted buffered response body write logic into a reusable method to avoid duplication
• Modified the Write method to pass through remaining bytes after partial processing
• Added comprehensive test coverage for various response body processing scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
http/interceptor.go	Added wroteBufferedBodyToDownstream flag to track state, created writeBufferedResponseBodyToDownstream() helper method, and updated Write() method to handle partial writes by passing through remaining bytes
http/interceptor_test.go	Added comprehensive TestResponseBody test function covering multiple scenarios including limit rejection, partial processing with and without data leaks, and chunked response handling

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