http_server and downstream: fix keepalive issues #4347

Job	Run time
pr-windows-build / Determine build info	8s
pr-windows-build / call-build-windows-package (Windows 32bit, x86, C:\vcpkg\packages\openssl_x86-windows-static, x86...	18m 14s
pr-windows-build / call-build-windows-package (Windows 64bit, x64, C:\vcpkg\packages\openssl_x64-windows-static, x64...	18m 55s
pr-windows-build / call-build-windows-package (Windows 64bit (Arm64), amd64_arm64, C:\vcpkg\packages\openssl_arm64-w...	17m 56s
pr-windows-build / Handle upload to S3	9s
run-windows-unit-tests / call-build-windows-unit-test (Windows 32bit, x86, C:\vcpkg\packages\openssl_x86-windows-static, x...	20m 4s
run-windows-unit-tests / call-build-windows-unit-test (Windows 64bit, x64, C:\vcpkg\packages\openssl_x64-windows-static, x...	17m 56s
	1h 33m 22s

Provide feedback