Equivalences clean up #1655

Job	Run time
nix	4m 12s
quick-build (supported, ubuntu-latest)	4m 16s
build (supported)	3m 46s
opam-build (supported, ubuntu-latest)	5m 36s
quick-build (latest, ubuntu-latest)	4m 18s
build (latest)	4m 53s
opam-build (8.17, ubuntu-latest)	7m 14s
quick-build (dev, ubuntu-latest)	3m 23s
build (dev, --warnings)	3m 48s
opam-build (latest, ubuntu-latest)	5m 47s
opam-build (dev, ubuntu-latest)	6m 25s
doc-coqdoc	1m 25s
coqchk (supported)	1m 41s
doc-dep-graphs	9m 25s
coqchk (latest)	1m 42s
doc-alectryon	25m 13s
coqchk (dev)	2m 6s
doc-timing	1m 30s
install (supported)	1m 14s
install (latest)	1m 32s
install (dev)	1m 11s
deploy-doc	0s
delete-artifacts	8s
	1h 40m 45s

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