cms: remove `alloc` feature (#1566) #1598

Job	Run time
build (1.81.0, thumbv7em-none-eabi)	34s
minimal-versions	0s
build (1.81.0, wasm32-unknown-unknown)	31s
test (1.81.0)	1m 13s
build (stable, thumbv7em-none-eabi)	25s
build (stable, wasm32-unknown-unknown)	24s
test (stable)	1m 10s
	4m 17s

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