Remove 'CLANG_BUILD' env variable usage #2465

Job	Run time
clang-format	12s
python-lint	4s
ubuntu-clang-build (ubuntu-24.04-arm)	1m 44s
ubuntu-clang-build (ubuntu-24.04)	1m 1s
ubuntu-gcc-build (ubuntu-24.04)	53s
ubuntu-gcc-build (ubuntu-24.04-arm)	1m 57s
windows-msvc-build	2m 52s
macos-clang-build	1m 44s
windows-clang-build	2m 23s
macos-clang-test	2m 51s
ubuntu-clang-test (ubuntu-24.04)	4m 26s
ubuntu-clang-sanitizer-build (ubuntu-24.04)	1m 3s
ubuntu-clang-test (ubuntu-24.04-arm)	5m 36s
ubuntu-gcc-test (ubuntu-24.04-arm)	6m 33s
ubuntu-gcc-test (ubuntu-24.04)	4m 19s
windows-clang-test	1m 28s
ubuntu-clang-sanitizer-test (ubuntu-24.04)	1m 48s
windows-msvc-test	2m 24s
windows-clang-test-extended	1m 16s
macos-clang-test-extended	1m 54s
ubuntu-clang-sanitizer-test-extended (ubuntu-24.04)	1m 43s
windows-msvc-test-extended	1m 15s
ubuntu-clang-test-extended (ubuntu-24.04-arm)	4m 5s
ubuntu-clang-test-extended (ubuntu-24.04)	2m 36s
ubuntu-gcc-test-extended (ubuntu-24.04-arm)	4m 40s
ubuntu-gcc-test-extended (ubuntu-24.04)	2m 25s
ubuntu-gcc-build-codecov	3m 29s
ubuntu-gcc-build-perf-stats	1m 7s
	1h 7m 48s

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