Remove unused `hazmat` feature #2768

Job	Run time
build (1.73.0, thumbv7em-none-eabi)	24s
build (1.73.0, wasm32-unknown-unknown)	25s
minimal-versions	0s
build (stable, thumbv7em-none-eabi)	23s
build (stable, wasm32-unknown-unknown)	18s
test (1.73.0)	28s
test (stable)	25s
test (nightly)	27s
	2m 50s

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