Equivalences clean up #1657

Job	Run time
build (supported)	3m 49s
opam-build (supported, ubuntu-latest)	6m 57s
build (latest)	3m 39s
quick-build (supported, ubuntu-latest)	3m 26s
opam-build (8.17, ubuntu-latest)	5m 22s
build (dev, --warnings)	3m 54s
quick-build (latest, ubuntu-latest)	4m 35s
nix	4m 17s
opam-build (latest, ubuntu-latest)	5m 15s
quick-build (dev, ubuntu-latest)	4m 34s
opam-build (dev, ubuntu-latest)	5m 42s
doc-alectryon	18m 16s
doc-coqdoc	1m 13s
coqchk (supported)	2m 9s
doc-dep-graphs	10m 26s
coqchk (latest)	1m 57s
coqchk (dev)	2m 8s
doc-timing	1m 13s
install (supported)	1m 8s
install (latest)	1m 27s
install (dev)	1m 32s
deploy-doc	0s
delete-artifacts	4s
	1h 33m 3s

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