WIP: replace cleanup scriptlets with shutdown script #8607

Job	Run time
validate commits	10s
Generate build matrix	6s
python linting	28s
spelling	6s
bookworm	12m 41s
bookworm - 32 bit	13m 2s
bookworm - gcc-12,content-s3,distcheck	15m 9s
bookworm - py3.11,clang-15	12m 56s
coverage	18m 44s
jammy - test-install	9m 58s
bookworm - test-install	10m 13s
focal - py3.8	13m 1s
el8	15m 41s
el8 - ascii	14m 26s
el8 - system,coverage	5m 57s
fedora34 - gcc-11.2,py3.9	13m 21s
fedora38 - gcc-13.1,py3.11	12m 17s
fedora39 - gcc-13.2,py3.12	13m 2s
alpine	11m 27s
inception	15m 49s
flux-pmix check	12m 55s
flux-accounting check	4m 18s
flux-pam check	4m 30s
flux-sched check	6m 31s
Generate docker manifest	1s
	3h 56m 49s

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