feature: install nix in determinate mode #1746

Job	Run time
build-lumina (40, silverblue)	11m 50s
build-lumina-nvidia (40, silverblue, open)	10m 27s
build-lumina (40, cosmic)	10m 45s
build-lumina-nvidia (40, cosmic, open)	9m 52s
build-lumina (41, silverblue)	10m 55s
build-lumina-nvidia (41, silverblue, open)	11m 4s
build-lumina-nvidia (41, cosmic, open)	10m 21s
build-lumina-nvidia (stable, silverblue, open)	9m 48s
build-lumina-nvidia (stable, cosmic, open)	12m 8s
build-lumina (41, cosmic)	10m 20s
build-lumina (stable, silverblue)	11m 9s
build-lumina (stable, cosmic)	11m 31s
check	11s
	2h 10m 21s

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