Fix timeoutSeconds

[skonto]

Fixes #15486

Proposed Changes

• Enforces killing the connection when timeout expires.

Release Note

[knative-prow]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.50%. Comparing base (3e45e8f) to head (4ffa8be).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15630      +/-   ##
==========================================
- Coverage   83.53%   83.50%   -0.04%     
==========================================
  Files         219      219              
  Lines       17427    17421       -6     
==========================================
- Hits        14558    14547      -11     
- Misses       2498     2504       +6     
+ Partials      371      370       -1     

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[skonto]

/retest

[skonto]

/retest

[skonto]

Conformance tests pass although body is set to "activator request timeout" as in the old PR here with maxDuration: https://github.com/knative/serving/pull/12322/files#diff-35466e0823800a5cd7310b69259cc638fb0657825c2c07c9a9d2bc99de3cfb0f
Response header can only be written once (a first write does it implicitly), so we cant return a 503.

In that PR I had:

name:               "writes first byte (HTTP OK), max duration violated, request can still timeout",
		timeoutSeconds:     10,
		maxDurationSeconds: 12,
		expectedStatus:     http.StatusOK,
		sleep:              15 * time.Second,
		initialSleep:       0,
		expectedBody:       "request timeout",