Remove namespace directives from util headers (#520) #3387

Job	Run time
lint / python-lint	6s
lint / clang-format	17s
lint / shell-lint	13s
mac / clang-build (Release)	2m 5s
mac / clang-build (Debug)	3m 4s
ubuntu / gcc-build (ubuntu-24.04, Debug)	1m 49s
ubuntu / clang-build (ubuntu-24.04-arm)	2m 50s
ubuntu / gcc-build (ubuntu-24.04, Release)	1m 44s
ubuntu / clang-build (ubuntu-24.04)	2m 35s
ubuntu / gcc-build (ubuntu-24.04-arm, Release)	2m 58s
windows / clang-build	2m 43s
windows / msvc-build (Release)	2m 18s
windows / msvc-build (Debug)	5m 27s
ubuntu / gcc-build (ubuntu-24.04-arm, Debug)	2m 20s
mac / clang-test	3m 35s
ubuntu / gcc-test (ubuntu-24.04-arm)	6m 6s
ubuntu / gcc-test (ubuntu-24.04)	5m 5s
ubuntu / clang-test (ubuntu-24.04-arm)	6m 38s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	1m 42s
ubuntu / clang-test (ubuntu-24.04)	5m 42s
windows / clang-test	2m 31s
mac / clang-test-extended	2m 21s
windows / msvc-test	3m 4s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	2m 43s
windows / clang-test-extended	1m 59s
ubuntu / gcc-test-extended (ubuntu-24.04)	3m 42s
ubuntu / gcc-test-extended (ubuntu-24.04-arm)	3m 50s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	2m 45s
windows / msvc-test-extended	1m 50s
ubuntu / clang-test-extended (ubuntu-24.04-arm)	4m 14s
ubuntu / clang-test-extended (ubuntu-24.04)	4m 0s
ubuntu / gcc-build-codecov	5m 7s
perf / ubuntu-gcc-build-perf-stats	1m 30s
pages / build-doxygen-xml	23s
pages / build-scoreboard	14s
pages / build-sphinx	41s
pages / deploy-pages	18s
	1h 40m 29s

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