add option for single-threading debugging #4193

Job	Run time
macOS / Release / homebrew-clang	5m 31s
macOS / Debug / homebrew-clang	7m 39s
macOS / Debug / system-clang	6m 20s
Windows / Debug / cl	14m 37s
macOS / Release / system-clang	6m 6s
Windows / Release / clang-cl	15m 3s
Release / ubuntu-24.04-arm / aarch64 / gcc	24m 55s
Windows / Release / cl	19m 36s
Debug / ubuntu-24.04-arm / aarch64 / clang	18m 30s
Release / ubuntu-24.04-arm / aarch64 / clang	17m 21s
Debug / ubuntu-24.04 / x86_64 / clang	19m 24s
Windows / Debug / clang	14m 12s
Release / ubuntu-24.04 / x86_64 / gcc	29m 56s
Windows / Debug / clang-cl	13m 1s
Release / ubuntu-24.04 / x86_64 / clang	23m 10s
Debug / ubuntu-24.04-arm / aarch64 / gcc	26m 45s
Debug / ubuntu-24.04 / x86_64 / gcc	21m 28s
Windows / Release / clang	16m 48s
	5h 0m 22s

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