cms: remove `alloc` feature (#1566) #3268

Job	Run time
test (1.81.0)	1m 8s
build (1.81.0, thumbv7em-none-eabi)	30s
build (1.81.0, wasm32-unknown-unknown)	27s
build (stable, thumbv7em-none-eabi)	19s
test (stable)	1m 4s
build (stable, wasm32-unknown-unknown)	28s
minimal-versions	0s
	3m 56s

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