http_client: assorted HTTP/2 related fixes #5061

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...	22m 7s
pr-windows-build / call-build-windows-package (Windows 64bit, x64, C:\vcpkg\packages\openssl_x64-windows-static, x64...	19m 54s
pr-windows-build / call-build-windows-package (Windows 64bit (Arm64), amd64_arm64, C:\vcpkg\packages\openssl_arm64-w...	22m 50s
pr-windows-build / Handle upload to S3	15s
run-windows-unit-tests / call-build-windows-unit-test (Windows 32bit, x86, C:\vcpkg\packages\openssl_x86-windows-static, x...	22m 7s
run-windows-unit-tests / call-build-windows-unit-test (Windows 64bit, x64, C:\vcpkg\packages\openssl_x64-windows-static, x...	18m 9s
	1h 45m 30s

Provide feedback