Partial migration to `rand_core` v0.9 #2638

Job	Run time
build (1.81.0, thumbv7em-none-eabi)	15s
derive (1.81.0)	14s
derive (stable)	28s
build (1.81.0, wasm32-unknown-unknown)	19s
build (stable, thumbv7em-none-eabi)	20s
build (stable, wasm32-unknown-unknown)	27s
test (1.81.0)	17s
test (stable)	12s
minimal-versions / minimal-versions	27s
	2m 59s

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