build cleaner, compilation db making: simplify #4891

Job	Run time
KytheVerification	0s
CheckFormatAndBuildClean	1m 53s
ClangTidy	4m 29s
x86_64 test	4m 2s
KytheXrefs	0s
MacOsBuild	4m 1s
arm64 test	4m 20s
📦 Pack Sources	4s
x86_64 test-clang	3m 29s
arm64 test-clang	4m 0s
x86_64 test-nortti	3m 30s
PrepareVSPlugin	2m 16s
x86_64 test-c++20	3m 22s
WindowsBuild	9m 37s
x86_64 test-c++23	3m 18s
x86_64 smoke-test	11m 13s
arm64 smoke-test	12m 28s
x86_64 asan	4m 58s
x86_64 asan-clang	4m 23s
x86_64 compile	4m 24s
arm64 compile	3m 43s
x86_64 compile-clang	3m 5s
arm64 compile-clang	3m 47s
x86_64 compile-static	3m 15s
arm64 compile-static	3m 47s
x86_64 compile-static-clang	3m 1s
arm64 compile-static-clang	3m 48s
x86_64 clean	7m 31s
arm64 clean	6m 55s
Build and deploy GitHub pages	8s
📦 Release	0s
	2h 4m 47s

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