AtomicCell: Use atomic-maybe-uninit #2500

Job	Run time
codegen	35s
dependencies	17s
careful	5m 17s
clippy	15s
docs	12s
features (1.61)	1m 29s
loom	56s
features (nightly)	24s
miri	19m 46s
san	13m 37s
shellcheck	10s
test (1.61, ubuntu-latest)	11m 53s
rustfmt	5s
test (1.61, windows-latest)	15m 46s
test (stable, ubuntu-latest)	9m 45s
test (stable, windows-latest)	14m 55s
test (nightly, ubuntu-latest)	9m 51s
test (nightly, windows-latest)	13m 42s
test (nightly, ubuntu-latest, i686-unknown-linux-gnu)	10m 19s
test (nightly, ubuntu-latest, armv7-unknown-linux-gnueabihf)	14m 59s
test (nightly, ubuntu-latest, armv5te-unknown-linux-gnueabi)	16m 43s
	2h 40m 56s

Provide feedback