Revert scheduler changes. (#4219) #11820

Job	Run time
build_js	2m 3s
build_details	3s
build_opam (4.14.x)	9m 12s
build_opam (5.2.x)	5m 46s
lezer_parse	53s
build_no_depopts	6m 13s
build_win32 (x64)	17m 56s
build_posix (debian_trixie, amd64)	15m 1s
run_tests (@citest)	12m 48s
build_posix (debian_bookworm, amd64)	14m 31s
run_tests (@doctest)	7m 40s
tree_sitter_parse	47s
build_posix (ubuntu_oracular, amd64)	14m 53s
update_doc	11m 25s
run_tests (@mediatest)	12m 44s
build_posix (ubuntu_noble, amd64)	14m 23s
build_posix (alpine, amd64)	12m 1s
fetch_s3_artifacts	20s
build_docker_alpine (amd64)	1m 22s
build_docker (amd64)	2m 2s
update_release	0s
build_docker_minimal (amd64)	2m 23s
build_docker_alpine_minimal (amd64)	1m 8s
build_docker_release	0s
build_docker_release-minimal	0s
	2h 45m 34s

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