Add GetNumProc util helper #3494

Job	Run time
lint / python-lint	9s
lint / clang-format	11s
lint / shell-lint	12s
mac / clang-build (Release)	2m 11s
mac / clang-build (Debug)	2m 6s
ubuntu / clang-build (ubuntu-24.04)	2m 57s
ubuntu / clang-build (ubuntu-24.04-arm)	2m 9s
ubuntu / gcc-build (ubuntu-24.04, Release)	1m 50s
ubuntu / gcc-build (ubuntu-24.04, Debug)	2m 47s
ubuntu / gcc-build (ubuntu-24.04-arm, Release)	1m 54s
windows / msvc-build (Release)	3m 24s
windows / msvc-build (Debug)	5m 52s
ubuntu / gcc-build (ubuntu-24.04-arm, Debug)	2m 57s
windows / clang-build	7m 44s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	3m 21s
ubuntu / clang-test (ubuntu-24.04-arm)	8m 56s
ubuntu / clang-test (ubuntu-24.04)	8m 44s
ubuntu / gcc-test (ubuntu-24.04-arm)	9m 12s
ubuntu / gcc-test (ubuntu-24.04)	9m 12s
mac / clang-test	5m 12s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	4m 11s
windows / msvc-test	4m 47s
windows / clang-test	2m 59s
mac / clang-test-extended	3m 2s
ubuntu / clang-test-extended (ubuntu-24.04)	5m 53s
ubuntu / clang-test-extended (ubuntu-24.04-arm)	5m 34s
windows / clang-test-extended	3m 30s
windows / msvc-test-extended	3m 2s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	3m 30s
ubuntu / gcc-test-extended (ubuntu-24.04)	4m 39s
ubuntu / gcc-test-extended (ubuntu-24.04-arm)	5m 29s
ubuntu / gcc-build-codecov	7m 37s
perf / ubuntu-gcc-build-perf-stats	2m 45s
pages / build-doxygen-xml	1m 31s
pages / build-scoreboard	12s
pages / build-sphinx	1m 26s
pages / deploy-pages	0s
	2h 21m 7s

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