elliptic-curve: use `crypto_common::Generate` #2617

Job	Run time
test (stable)	16s
test (1.85.0)	23s
build (1.85.0, thumbv7em-none-eabi)	19s
build (stable, wasm32-unknown-unknown)	18s
build (stable, thumbv7em-none-eabi)	11s
build (1.85.0, wasm32-unknown-unknown)	20s
	1m 47s

Provide feedback