Make readability-function-cognitive-complexity threshold more strict … #2178

Job	Run time
python-lint	5s
clang-format	11s
ubuntu-clang-build	2m 9s
ubuntu-gcc-build	2m 9s
windows-msvc-build	3m 29s
windows-clang-build	4m 18s
macos-clang-build	2m 18s
ubuntu-clang-sanitizer-build	1m 51s
ubuntu-clang-test	4m 39s
ubuntu-gcc-test	4m 53s
macos-clang-test	2m 54s
windows-msvc-test	2m 16s
ubuntu-clang-sanitizer-test	3m 2s
windows-clang-test	1m 31s
macos-clang-test-extended	2m 53s
windows-msvc-test-extended	2m 16s
windows-clang-test-extended	2m 11s
ubuntu-clang-test-extended	4m 50s
ubuntu-gcc-test-extended	5m 26s
ubuntu-clang-sanitizer-test-extended	2m 44s
ubuntu-gcc-build-codecov	5m 8s
ubuntu-gcc-build-perf-stats	3m 3s
	1h 4m 16s

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