Remove last uses of `GridArray` type alias. #259

Job	Run time
miri	1m 33s
build (ubuntu, stable, locked, true)	13m 44s
no_std	27s
build (windows, stable, locked, false)	25m 5s
build (macos, stable, locked, false)	26m 54s
build (ubuntu, nightly, locked, false)	13m 6s
build (ubuntu, beta, locked, false)	12m 58s
build (ubuntu, stable, latest, false)	21m 51s
build (ubuntu, stable, minimal, false)	13m 55s
features	24m 45s
deploy	4s
fuzz	15m 27s
	2h 49m 49s

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